limitations of rutherford scattering experiment

• Structure of Atom
• Rutherford Atomic Model And Its Limitations

Rutherford Atomic Model and Limitations

Define rutherford atomic model.

Rutherford Atomic Model – The plum pudding model given by J. J. Thomson failed to explain certain experimental results associated with the atomic structure of elements. Ernest Rutherford, a British scientist conducted an experiment and based on the observations of this experiment, he explained the atomic structure of elements and proposed Rutherford’s Atomic Model.

Table of Contents

• Rutherfords Alpha Scattering Experiment

Observations of Rutherford’s Alpha Scattering Experiment

Rutherford atomic model, limitations of rutherford atomic model, recommended videos, frequently asked questions – faqs.

Rutherford’s Alpha Scattering Experiment

Rutherford conducted an experiment by bombarding a thin sheet of gold with α-particles and then studied the trajectory of these particles after their interaction with the gold foil.

Rutherford, in his experiment, directed high energy streams of α-particles from a radioactive source at a thin sheet (100 nm thickness) of gold. In order to study the deflection caused to the α-particles, he placed a fluorescent zinc sulphide screen around the thin gold foil. Rutherford made certain observations that contradicted Thomson’s atomic model .

The observations made by Rutherford led him to conclude that:

• A major fraction of the α-particles bombarded towards the gold sheet passed through the sheet without any deflection, and hence most of the space in an atom is empty .
• Some of the α-particles were deflected by the gold sheet by very small angles, and hence the positive charge in an atom is not uniformly distributed . The positive charge in an atom is concentrated in a very small volume .
• Very few of the α-particles were deflected back, that is only a few α-particles had nearly 180 o angle of deflection. So the volume occupied by the positively charged particles in an atom is very small as compared to the total volume of an atom .

Based on the above observations and conclusions, Rutherford proposed the atomic structure of elements. According to the Rutherford atomic model:

• The positive charge and most of the mass of an atom is concentrated in an extremely small volume. He called this region of the atom as a nucleus.
• Rutherford’s model proposed that the negatively charged electrons surround the nucleus of an atom. He also claimed that the electrons surrounding the nucleus revolve around it with very high speed in circular paths. He named these circular paths as orbits.
• Electrons being negatively charged and nucleus being a densely concentrated mass of positively charged particles are held together by a strong electrostatic force of attraction.

Although the Rutherford atomic model was based on experimental observations, it failed to explain certain things.

• Rutherford proposed that the electrons revolve around the nucleus in fixed paths called orbits. According to Maxwell, accelerated charged particles emit electromagnetic radiations and hence an electron revolving around the nucleus should emit electromagnetic radiation. This radiation would carry energy from the motion of the electron which would come at the cost of shrinking of orbits. Ultimately the electrons would collapse in the nucleus. Calculations have shown that as per the Rutherford model, an electron would collapse into the nucleus in less than 10 -8 seconds. So the Rutherford model was not in accordance with Maxwell’s theory and could not explain the stability of an atom .
• One of the drawbacks of the Rutherford model was also that he did not say anything about the arrangement of electrons in an atom which made his theory incomplete.
• Although the early atomic models were inaccurate and failed to explain certain experimental results, they formed the base  for future developments in the world of quantum mechanics .

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The Gold Foil Experiment

Structure of Atom Class 11 Chemistry

Drawbacks of Rutherford Atomic Model

What was the speciality of Rutherford’s atomic model?

Rutherford was the first to determine the presence of a nucleus in an atom. He bombarded α-particles on a gold sheet, which made him encounter the presence of positively charged specie inside the atom.

What is Rutherford’s atomic model?

Rutherford proposed the atomic structure of elements. He explained that a positively charged particle is present inside the atom, and most of the mass of an atom is concentrated over there. He also stated that negatively charged particles rotate around the nucleus, and there is an electrostatic force of attraction between them.

What are the limitations of Rutherford’s atomic model?

Rutherford failed to explain the arrangement of electrons in an atom. Like Maxwell, he was unable to explain the stability of the atom.

What kind of experiment did Rutherford’s perform?

Rutherford performed an alpha scattering experiment. He bombarded α-particles on a gold sheet and then studied the trajectory of these α-particles.

What was the primary observation of Rutherford’s atomic model?

Rutherford observed that a microscopic positively charged particle is present inside the atom, and most of the mass of an atom is concentrated over there.

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I am very happy with the answer that I obtained, however Ernest Rutherford’s Atomic Model never had any neutrons in the nucleus. James Chadwick discovered the neutron later in 1932. However, the limitations and observations of his theory on this web page seem to be correct.

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What is the model of the atom proposed by Ernest Rutherford?

What is the rutherford gold-foil experiment, what were the results of rutherford's experiment, what did ernest rutherford's atomic model get right and wrong, what was the impact of ernest rutherford's theory.

Rutherford model

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• UC Davis - The Rutherford Scattering Experiment
• Chemistry LibreTexts - Rutherford's Experiment- The Nuclear Model of the Atom

The atom , as described by Ernest Rutherford , has a tiny, massive core called the nucleus . The nucleus has a positive charge. Electrons are particles with a negative charge. Electrons orbit the nucleus. The empty space between the nucleus and the electrons takes up most of the volume of the atom.

A piece of gold foil was hit with alpha particles , which have a positive charge. Most alpha particles went right through. This showed that the gold atoms were mostly empty space. Some particles had their paths bent at large angles. A few even bounced backward. The only way this would happen was if the atom had a small, heavy region of positive charge inside it.

The previous model of the atom, the Thomson atomic model , or the “plum pudding” model, in which negatively charged electrons were like the plums in the atom’s positively charged pudding, was disproved. The Rutherford atomic model relied on classical physics. The Bohr atomic model , relying on quantum mechanics, built upon the Rutherford model to explain the orbits of electrons.

The Rutherford atomic model was correct in that the atom is mostly empty space. Most of the mass is in the nucleus, and the nucleus is positively charged. Far from the nucleus are the negatively charged electrons. But the Rutherford atomic model used classical physics and not quantum mechanics. This meant that an electron circling the nucleus would give off electromagnetic radiation . The electron would lose energy and fall into the nucleus. In the Bohr model, which used quantum theory, the electrons exist only in specific orbits and can move between these orbits.​

The gold-foil experiment showed that the atom consists of a small, massive, positively charged nucleus with the negatively charged electrons being at a great distance from the centre. Niels Bohr built upon Rutherford’s model to make his own. In Bohr’s model the orbits of the electrons were explained by quantum mechanics.

Rutherford model , description of the structure of atoms proposed (1911) by the New Zealand-born physicist Ernest Rutherford . The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents , called electrons , circulate at some distance, much like planets revolving around the Sun .

The nucleus was postulated as small and dense to account for the scattering of alpha particles from thin gold foil, as observed in a series of experiments performed by undergraduate Ernest Marsden under the direction of Rutherford and German physicist Hans Geiger in 1909. A radioactive source emitting alpha particles (i.e., positively charged particles, identical to the helium atom nucleus and 7,000 times more massive than electrons) was enclosed within a protective lead shield. The radiation was focused into a narrow beam after passing through a slit in a lead screen. A thin section of gold foil was placed in front of the slit, and a screen coated with zinc sulfide to render it fluorescent served as a counter to detect alpha particles. As each alpha particle struck the fluorescent screen , it produced a burst of light called a scintillation, which was visible through a viewing microscope attached to the back of the screen. The screen itself was movable, allowing Rutherford and his associates to determine whether or not any alpha particles were being deflected by the gold foil.

Most alpha particles passed straight through the gold foil, which implied that atoms are mostly composed of open space. Some alpha particles were deflected slightly, suggesting interactions with other positively charged particles within the atom. Still other alpha particles were scattered at large angles, while a very few even bounced back toward the source. (Rutherford famously said later, “It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.”) Only a positively charged and relatively heavy target particle, such as the proposed nucleus, could account for such strong repulsion. The negative electrons that balanced electrically the positive nuclear charge were regarded as traveling in circular orbits about the nucleus. The electrostatic force of attraction between electrons and nucleus was likened to the gravitational force of attraction between the revolving planets and the Sun. Most of this planetary atom was open space and offered no resistance to the passage of the alpha particles.

The Rutherford model supplanted the “plum-pudding” atomic model of English physicist Sir J.J. Thomson , in which the electrons were embedded in a positively charged atom like plums in a pudding. Based wholly on classical physics , the Rutherford model itself was superseded in a few years by the Bohr atomic model , which incorporated some early quantum theory . See also atomic model .

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Rutherford Scattering

Michael Fowler, University of Virginia

Rutherford as Alpha-Male

[Rutherford was] a "tribal chief", as a student said.

(Richard Rhodes, The Making of the Atomic Bomb, page 46)

In 1908 Rutherford was awarded the Nobel Prize—for chemistry! The award citation read: "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances." While at McGill University, he had discovered that the radioactive element thorium emitted a gas which was itself radioactive, but if the gas radioactivity was monitored separately from the thorium's, he found it decreased geometrically, losing approximately half its current strength for each minute that passed. The gas he had found was a short-lived isotope of radon, and this was the first determination of a "half-life" for a radioactive material. (Pais, Inward Bound , page 120).

The chemists were of course impressed that Rutherford was fulfilling their ancient alchemical dream of transmuting elements, or at least demonstrating that it happened. Rutherford himself remarked at the ceremony that he "had dealt with many different transformations with various time-periods, but the quickest he had met was his own transformation from a physicist to a chemist". Still, Nobel prizes of any kind are nice to get, so he played along, titling his official Nobel lecture: "The chemical nature of the alpha-particle from radioactive substances". (He established that his favorite particle was an ionized helium atom by collecting alphas in an evacuated container, where they picked up electrons. After compressing this very rarefied gas, he passed an electric discharge through it and observed the characteristic helium spectrum in the light emitted.)

Rutherford was the world leader in alpha-particle physics. In 1906, at McGill University, Montreal, he had been the first to detect slight deflections of alphas on passage through matter. In 1907, he became a professor at the University of Manchester, where he worked with Hans Geiger . This was just a year after Rutherford's old boss, J. J. Thomson , had written a paper on his plum pudding atomic model suggesting that the number of electrons in an atom was about the same as the atomic number. (Not long before, people had speculated that atoms might contain thousands of electrons. They were assuming that the electrons contributed a good fraction of the atom's mass.) The actual distribution of the electrons in the atom, though, was as mysterious as ever.  Mayer's floating magnets (see previous lecture) were fascinating, but had not led to any quantitative conclusions on electronic distributions in atoms.

Rutherford's 1906 discovery that his pet particles were slightly deflected on passing through atoms came about when he was finding their charge to mass ratio, by measuring the deflection in a magnetic field. He detected the alphas by letting them impact photographic film. When he had them pass through a thin sheet of mica before hitting the film (so the film didn't have to be in the vacuum?) he found the image was blurred at the edges, evidently the mica was deflecting the alphas through a degree or two. He also knew that the alphas wouldn't be deflected a detectable amount by the electrons in the atom, since the alphas weighed 8,000 times as much as the electrons, atoms contained only a few dozen electrons, and the alphas were very fast. The mass of the atom must be tied up somehow with the positive charge . Therefore, he reasoned, analyzing these small deflections might give some clue as to the distribution of positive charge and mass in the atom, and therefore give some insight into his old boss J. J.'s plum pudding. The electric fields necessary in the atom for the observed scattering already seemed surprisingly high to Rutherford (Pais, page 189).

Scattering Alphas

Rutherford's alpha scattering experiments were the first experiments in which individual particles were systematically scattered and detected. This is now the standard operating procedure of particle physics. To minimize alpha loss by scattering from air molecules, the experiment was carried out in a fairly good vacuum, the metal box being evacuated through a tube T (see below). The alphas came from a few milligrams of radium (to be precise, its decay product radon 222) at R in the figure below, from the original paper, which goes on:

" By means of a diaphragm placed at D, a pencil of alpha particles was directed normally on to the scattering foil F. By rotating the microscope [M] the alpha particles scattered in different directions could be observed on the screen S."

Actually, this was more difficult than it sounds. A single alpha caused a slight fluorescence on the zinc sulphide screen S at the end of the microscope. This could only be reliably seen by dark-adapted eyes (after half an hour in complete darkness) and one person could only count the flashes accurately for one minute before needing a break, and counts above 90 per minute were too fast for reliability. The experiment accumulated data from hundreds of thousands of flashes.

Rutherford's partner in the initial phase of this work was Hans Geiger, who later developed the Geiger counter to detect and count fast particles. Many hours of staring at the tiny zinc sulphide screen in the dark must have focused his mind on finding a better way!

In 1909, an undergraduate, Ernest Marsden, was being trained by Geiger. To quote Rutherford (a lecture he gave much later):

"I had observed the scattering of alpha-particles, and Dr. Geiger in my laboratory had examined it in detail. He found, in thin pieces of heavy metal, that the scattering was usually small, of the order of one degree.

"One day Geiger came to me and said, "Don't you think that young Marsden , whom I am training in radioactive methods, ought to begin a small research?" Now I had thought that, too, so I said, " Why not let him see if any alpha-particles can be scattered through a large angle?"

"I may tell you in confidence that I did not believe that they would be, since we knew the alpha-particle was a very fast, massive particle with a great deal of energy, and you could show that if the scattering was due to the accumulated effect of a number of small scatterings, the chance of an alpha-particle's being scattered backward was very small. Then I remember two or three days later Geiger coming to me in great excitement and saying "We have been able to get some of the alpha-particles coming backward …" It was quite the most incredible event that ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."

Disproof of the Pudding

The back scattered alpha-particles proved fatal to the plum pudding model. A central assumption of that model was that both the positive charge and the mass of the atom were more or less uniformly distributed over its size, approximately 10 -10  meters across or a little more. It is not difficult to calculate the magnitude of electric field from this charge distribution. (Recall that this is the field that must scatter the alphas, the electrons are so light they will jump out of the way with negligible impact on an alpha.)

To be specific, let us consider the gold atom, since the foil used by Rutherford was of gold, beaten into leaf about 400 atoms thick. The gold atom has a positive charge of 79 e (balanced of course by that of the 79 electrons in its normal state). Neglect the electrons—they'll be scattered away with negligible impact on the heavy alpha.

See the animation here !

The maximum electric force the alpha will encounter is that at the surface of the sphere of positive charge,

E ⋅ 2 e = 1 4 π ε 0 ⋅ 79 e ⋅ 2 e r 0 2 = 9 ⋅ 10 9 158 ⋅ ( 1.6 ⋅ 10 − 19 ) 10 − 20 = 3.64 ⋅ 10 − 6  Newtons .  

(In this model, once inside the sphere the electric force goes down, just as gravity goes down on going deep into the earth, to zero at the center. But the sideways component stays approximately constant if the path is nearly a straight line.)

If the alpha particle initially has momentum  p , for small deflections the angle of deflection (in radians) is given by Δ p / p ,  where  Δ p is the sideways momentum resulting from the electrically repulsive force of the positive sphere of charge.

A good estimate of the sideways deflection is given by taking the alpha to experience the surface  force given above for a time interval equal to the time it takes the alpha to cross the atom—say, a distance 2 r 0 .   (The force felt when outside the ball of charge is much smaller: it drops away as the inverse square, but at an angle that makes it effectively inverse cube. It can be shown to make only a small contribution.)

Note that since the alpha particle has mass 6.7x10 -27  kg, from  F = m a , the electric force at the atomic surface above will give it a sideways acceleration of 5.4x10 20  meters per sec per sec (compare  g = 10 !). But the force doesn't have long to act—the alpha is moving at 1.6x10 7  meters per second. So the time available for the force to act is the time interval a particle needs to cross an atom if the particle gets from New York to Australia in one second.

So the transit time for the alpha across the plum pudding atom is:

t 0 = 2 r 0 / v = 2 × 10 10 / 1.6 × 10 7 = 1.25 × 10 − 17  seconds .  

Now, the magnitude of the total sideways velocity picked up on crossing the atom is the sideways acceleration multiplied by the time,

1.25 × 10 − 17 × 5.4 × 10 20 = 6750   m /sec .  

This is a few ten-thousandths of the alpha's forward speed , so there is only a very tiny deflection . Even if the alpha hit 400 atoms in succession and they all deflected it the same way, an astronomically improbable event, the deflection would only be of order a degree. Therefore, the observed deflection through ninety degrees and more was completely inexplicable using Thomson's pudding model!

Emergence of the Nucleus

Rutherford pondered the problem for some months. He had been a believer in his former boss's pudding model, but he eventually decided there was simply no way it could generate the strength of electric field necessary to deflect the fast moving alphas. Yet it was difficult to credit there was much more positive charge around than that necessary to compensate for the electrons, and it was pretty well established that there were not more than a hundred or so electrons (we used 79, the correct value—that was not known exactly until a little later). The electric field from a sphere of charge reaches its maximum on the surface, as discussed above. Therefore, for a given charge, assumed spherically distributed, the only way to get a stronger field is to compress it into a smaller sphere . Rutherford concluded that he could only explain the large alpha deflections if the positive charge, and most of the mass of the atom, was in a sphere much smaller than the atom itself .

It is not difficult to estimate from the above discussion how small such a nucleus would have to be to give a substantial deflection. We found a sphere of radius 10 -10  meters gave a deflection of about 4x10 -4  radians. We need to increase this deflection by a factor of a few thousand. On decreasing the radius of the sphere of positive charge, the force at the surface increases as the inverse radius squared . On the other hand, the time over which the alpha experiences the sideways force decreases as the radius.

The total deflection , then, proportional to the product of force and time, increases as the inverse of the radius . This forces the conclusion that the positive charge is in a sphere of radius certainly less than 10 -13  meters, provided all the observed scattering is caused by one encounter with a nucleus.

Animation of scattering from a nuclear atom here !

Rutherford decided that the observed scattering was in fact from a single nucleus. He argued as follows: since the foil is only 400 atoms thick, it is difficult to see how ninety degree scatterings could arise unless the scattering by a single nucleus was at least one degree, say 100 times that predicted by the Thomson model. This would imply that the nucleus had a radius at most one-hundredth that of the atom, and therefore presented a target area for one-degree scattering (or more) to the incoming alphas only one ten-thousandth that of the atom. (In particle physics jargon, this target area is called the scattering cross section .) If an alpha goes through 400 layers of atoms, and in each layer it has a chance of one in ten thousand of getting close enough to the nucleus for a one-degree scatter, this is unlikely to happen twice. It follows that almost certainly only one scattering takes place. It then follows that all ninety or more degrees of scattering must be a single event, so the nucleus must be even smaller than one hundredth the radius of the atom -- it must be less than 10 -13 meters, as stated above.

Seeing the Nucleus

Having decided that the observed scattering of the alphas came from single encounters with nuclei, and assuming that the scattering force was just the electrostatic repulsion, Rutherford realized maybe just scaling down the radius in the plum pudding analysis given above wasn't quite right. Maybe the nucleus was so small that the alpha particle didn't even touch it. If that were the case, the alpha particle's entire trajectory was determined by a force law of inverse square repulsion, and could be analyzed precisely mathematically by the techniques already well-known to astronomers for finding paths of planets under inverse square attraction.

It turns out that the alpha will follow a hyperbolic path (see the animation). Imagine an alpha coming in along an almost straight line path, the perpendicular distance of the nucleus from this line is called the impact parameter (how close to the center the alpha particle would pass if the repulsion were switched off).  The standard planetary math is enough to find the angle at which the alpha comes out (the scattering angle), given the impact parameter and speed.  Although not exactly a hot shot theorist, Rutherford managed to figure this out after a few weeks.

The incoming stream of alphas all have the same velocity (including direction) , but random impact parameters: we assume the beam intensity doesn't vary much in the perpendicular direction, certainly on an atomic scale, so we average over impact parameters (with a factor 2 π p d p  for the annular region   p , p + d p  ).

The bottom line is that for a nucleus of charge  Z , and incident alpha particles of mass  m and speed  v , the rate of scattering to a point on the screen corresponding to a scattering angle of  θ (angle between incident velocity and final velocity of alpha) is proportional to:

scattering into small area at  θ   ∝ ( 1 4 π ε 0 ⋅ Z e 2 m v 2 ) 2 ⋅ 1 sin 4 ( θ / 2 ) .  

Analysis of the hundred thousand or more scattering events recorded for the alphas on gold fully confirmed the angular dependence predicted by the above analysis.

Modeling the Scattering

To visualize the path of the alpha in such a scattering, Rutherford "had a model made, a heavy electromagnet suspended as a pendulum on thirty feet of wire that grazed the face of another electromagnet set on a table. With the two grazing faces matched in polarity and therefore repelling each other, the pendulum was deflected" into a hyperbolic path.(Rhodes, page 50)

But it didn't work for Aluminum...

On replacing the gold foil by aluminum foil (some years later), it turned out that small angle scattering obeyed the above law, but large angle scattering didn't. Rutherford correctly deduced that in the large angle scattering, which corresponded to closer approach to the nucleus, the alpha was actually hitting the nucleus. This meant that the size of the nucleus could be worked out by finding the maximum angle for which the inverse square scattering formula worked, and finding how close to the center of the nucleus such an alpha came. Rutherford estimated the radius of the aluminum nucleus to be about 10 -14  meters.

The Beginnings of Nuclear Physics

The First World War lasted from 1914 to 1918. Geiger and Marsden were both at the Western front, on opposite sides. Rutherford had a large water tank installed on the ground floor of the building in Manchester, to carry out research on defense against submarine attack. Nevertheless, occasional research on alpha scattering continued. Scattering from heavy nuclei was fully accounted for by the electrostatic repulsion, so Rutherford concentrated on light nuclei, including hydrogen and nitrogen. In 1919, Rutherford established that an alpha impinging on a nitrogen nucleus can cause a hydrogen atom to appear! Newspaper headlines blared that Rutherford had "split the atom". (Rhodes, page 137)

Shortly after that experiment, Rutherford moved back to Cambridge to succeed J. J. Thomson as head of the Cavendish laboratory, working with one of his former students, James Chadwick , who had spent the war years interned in Germany. They discovered many unusual effects with alpha scattering from light nuclei. In 1921, Chadwick and co-author Bieler wrote: "The present experiments do not seem to throw any light on the nature of the law of variation of the forces at the seat of an electric charge, but merely show that the forces are of great intensity … It is our task to find some field of force which will reproduce these effects." I took this quote from Pais, page 240, who goes on to say that he considers this 1921 statement as marking the birth of the strong interactions.

In fact, Rutherford was beginning to focus his attention on the actual construction of the nucleus and the alpha particle. He coined the word "proton" to describe the hydrogen nucleus, it first appeared in print in 1920 (Pais). At first, he thought the alpha must be made up of four of these protons somehow bound together by having two electrons in the middle—this would get the mass and charge right, but of course nobody could construct a plausible electrostatic configuration. Then he had the idea that maybe there was a special very tightly bound state of a proton and an electron, much smaller than an atom. By 1924, he and Chadwick were discussing how to detect this neutron. It wasn't going to be easy—it probably wouldn't leave much of a track in a cloud chamber. In fact, Chadwick did discover the neutron, but not until 1932, and it wasn't much like their imagined proton-electron bound state. But it did usher in the modern era in nuclear physics.

Rutherford Atomic Model

Definition of the rutherford model.

The Rutherford atomic model has 2 main parts: the nucleus, and the atom’s remaining space, occupied by electrons.

According to the model, the nucleus is a very small portion of the atom’s volume. It occupies a small space in the very center of the atom. Protons and neutrons make up the nucleus and define the atom’s chemical properties.

Rutherford also claimed in his model that electrons revolved around the nucleus in set orbits, like planets revolving around the Sun. This part of the theory was inaccurate, as explained in the last section.

Rutherford’s Gold Foil Experiment

The Rutherford gold foil experiment , also known as the scattering experiment, led to the creation of the model and explained the parts of the atom. In 1909, graduate student Ernest Marsden (under Ernest Rutherford’s supervision) fired alpha particles at a gold foil piece. Most of the particles passed directly through the foil, meaning that a majority of the space in each atom was unoccupied. However, a few particles were deflected, and some even backward. This must have been caused by tiny pockets of positive charge in the foil repelling the alpha particles back. Their discovery led to the creation of Rutherford’s model, in which the dense, positively-charged nucleus occupies a very small area in the center of each atom.

Shortcomings of the Rutherford Model

While common models today are based on the Rutherford atomic theory, it does not paint the complete picture:

• The model is missing parts and does not account for the location or distribution of electrons.
• Rutherford proposed that electrons orbit around the nucleus in set paths, but according to Maxwell’s theory , this is not possible because the atom would not be stable. Electromagnetic radiation from the electrons in orbit would cause the atom to collapse into the nucleus in 10 -8 seconds.
• Electrons increase and decrease energy levels randomly due to the acceleration and are not always in a standard circular orbit. They give off electromagnetic radiation due to the circular motion of orbiting; thus they must have some initial energy by the law of conservation of energy. The Rutherford atomic model does not account for the initial energy and subsequent energy level changes.

Further Reading

• Dalton’s Atomic Theory
• Bohr Atomic Model
• The Structure of an Atom

• Rutherford’s Model of Atoms and its Limitations

Rutherford’s atomic model, also known as the nuclear atom or planetary model, was proposed by Ernest Rutherford in 1911. This model describes the atom as a small, dense, positively charged nucleus at the center, with negatively charged electrons orbiting around it, similar to how planets orbit the sun.

• Rutherford’s Alpha Scattering Experiment Explanation

Key Experiments: The Gold Foil Experiment

In the gold foil experiment, Rutherford and his team bombarded a thin sheet of gold foil with alpha particles (positively charged particles). They observed how these particles were scattered after hitting the foil.

• A radioactive source emitted alpha particles, which were directed towards the gold foil through a slit in a lead screen.
• A zinc sulfide-coated screen detected the particles by producing flashes of light when hit by alpha particles, visible through a microscope.

Observations:

• Most alpha particles passed through the foil without deflection, suggesting that atoms are mostly empty space.
• Some particles experienced slight deflections, indicating the presence of a positive charge within the atom.
• A few particles were deflected at large angles or bounced back, implying that the positive charge is concentrated in a small, dense region.
• Conclusions from the Experiment

Rutherford concluded that:

• The atom has a small, dense nucleus containing most of its mass and positive charge.
• Electrons orbit this nucleus at a distance, occupying most of the atom’s volume.
• The number of electrons equals the number of protons in the nucleus, making the atom electrically neutral.
• Features of Rutherford’s Atomic Model
• The nucleus is very small and dense, containing all the positive charge due to protons.
• Different elements have different numbers of protons, giving them different positive charges.
• Electrons, which are negatively charged, orbit the nucleus at high speeds.
• Most of the atom is empty space.
• Drawbacks of Rutherford’s Atomic Model
• Stability of Atoms: The model couldn’t explain why atoms are stable. According to classical physics, orbiting electrons should lose energy and spiral into the nucleus, causing the atom to collapse.
• Hydrogen Spectrum: The model also couldn’t explain the existence of specific spectral lines in the hydrogen atom’s emission spectrum.

Rutherford’s model was a significant step forward in understanding atomic structure, but it was later refined by Niels Bohr, who introduced concepts from quantum theory to address its limitations.

What is the significance of the hydrogen spectrum problem?

The hydrogen spectrum problem refers to the fact that Rutherford’s model could not explain why hydrogen atoms emit light at specific wavelengths, forming a series of discrete spectral lines. This was later explained by Bohr’s model using quantum theory.

Why couldn’t Rutherford’s model explain the stability of atoms?

According to classical physics, orbiting electrons should continuously emit energy and lose speed, eventually collapsing into the nucleus. This would make atoms unstable, which contradicts the observed stability of matter.

How did Rutherford’s model influence future atomic theories?

Rutherford’s model laid the groundwork for future atomic theories by introducing the concept of a nucleus. It was later refined by Niels Bohr, who incorporated quantum theory to explain the stability of atoms and the hydrogen spectrum.

Why is the nucleus important in Rutherford’s model?

The nucleus is important because it contains almost all the mass of the atom and the positive charge, which influences the behavior and arrangement of the electrons.

How was Rutherford’s atomic model developed?

Rutherford developed his model based on the gold foil experiment conducted in 1909. This experiment involves bombarding a thin gold foil with alpha particles and observing their scattering patterns.

What is Rutherford’s atomic model?

Rutherford’s atomic model, also known as the nuclear atom or planetary model, describes the atom as having a small, dense nucleus at the center, containing all the positive charge, with electrons orbiting around it, similar to how planets orbit the sun.

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• Drawbacks of Rutherford's Atomic Model

What is Rutherford’s Atomic Model?

Rutherford Atomic model is also known as the Rutherford model, nuclear atom , or planetary model of the atom was established in the year 1911 which explained the structure of atoms and was developed by the New Zealand-born physicist Ernest Rutherford. The model derived that the atom is nothing but a small tiny dense mass that has a positively charged body present in the core which is presently known as the nucleus where the entire mass of the atom is concentrated and around it revolves the negatively charged light electrons at a certain distance much like the planets revolving around the sun. 

In the gold foil experiment, the nucleus was postulated as a dense and small mass which was responsible for the scattering of the alpha particles. It was observed in a series of experiments that were carried out by the undergraduate Ernest Marsden under the guidance of Rutherford and German physicist Hans Geiger in 1909. The Rutherford model as a supplement for the  “plum-pudding” atomic model of English physicist Sir J.J. Thomson worked on the fact claimed by the plum-pudding atomic model that the electrons are embedded into the positively charged mass that was claimed as the atom-like plums in a pudding. 

Rutherford's model was also obsoleted by Bhor’s atomic model purely based on classical physics. Bohr’s atomic model has also been seen to be incorporating some of the early concepts of quantum theory.     

(Image will be uploaded soon)

Rutherford’s Alpha Scattering Experiment Explanation

Rutherford conducted a light scattering experiment where he placed a gold foil and bombarded the gold sheet with the alpha particles. The trajectory of the alpha particles was then studied after they interacted with the gold foil. There was a radioactive source that emitted Alpha particles which are positively charged particles that were enclosed within a lead shield in a protective manner.

The radiation then passed in a narrow beam after it passed through a slit which was made in the lead screen. A very thin section of a gold foil is placed before the lead screen and the LED screen was covered with zinc sulphide so as to give it a fluorescent nature that served as a counter detection to the Alpha particles. 

As soon as the Alpha particles right the fluorescent screen it's shattered into a burst of light which is known as scintillation. It was visible from the viewing microscope that was attached to the back of the screen. As the screen was movable, it allowed Rutherford to study whether or not Alpha particles get deflected by the gold foil.

Observations of Rutherford’s Alpha Scattering Experiment

The observation that was made by Rutherford let him conclude that:-

Most of the Alpha particles that bombarded the gold fell passed through without any deflection that shows that the nucleus is made up of a large empty space.

Few of the Alpha particles that bombarded against the gold foil experienced a very minor deflection that shows that there is a presence of a counter positive charge.

Still, some of the Alpha particles that bombarded against the gold foil deflected to a larger angle and some of them even bounced back showing that the positive charge is concentrated in a very small volume and its distribution is non-uniform.

All the above points show that the volume occupied by positively charged particles in an atom is very small as compared to the total volume of the atom.

Result of Rutherford’s Alpha Scattering Experiment 

On the basis of his experiment, observation and result, Rutherford put forward Rutherford’s atomic model, which had the following features:

The entire mass and positive charge of an atom are concentrated in a very small region at the centre known as the nucleus. 

The positive charge on the nucleus is due to protons. Since the number of protons is different for atoms of different elements, therefore, the magnitude of positive charge on the nucleus is different for atoms of different elements. 

The nucleus is surrounded by negatively charged electrons. The number of electrons in an atom is equal to the number of protons (positively charged) in the nucleus. Thus, the atom as a whole is neutral. 

The electrons are revolving around the nucleus at a very high speed. 

Most of the space in an atom is empty.

Drawbacks of Rutherford’s Atomic Model

Rutherford’s Atomic Model had the Following Limitations:

This atomic model failed to explain the stability of atoms.

According to the model, electrons revolve around the positively charged nucleus. It's not possible for the long run as we know atoms are stable while any particle in a circular orbit would undergo acceleration. During acceleration charged particles would radiate energy. Revolving electrons will lose energy and finally fall into the nucleus. 

This model of the atom also failed to explain the existence of definite lines in the hydrogen spectrum.

This was all about Rutherford’s atomic model. If you are looking for NCERT Solutions of Science Class IX, then download the Vedantu learning app or register yourself on Vedantu.

FAQs on Drawbacks of Rutherford's Atomic Model

1. What does Rutherford’s model explain?

It explains that an atom is composed of a very tiny mass of an atom where all the mass of the atom is concentrated and that is known as the nucleus around which the electrons revolve and have an ample amount of free space.

2. What is the conclusion of the Rutherford model?

The main conclusion of the Rutherford model is that an atom is composed of a very tiny mass of an atom where all the mass of the atom is concentrated and that is known as the nucleus.

NCERT Study Material

Rutherford Atomic Model| Experiment| Success & Limitation

• Post author: Shunil Shah
• Post last modified: January 14, 2024
• Reading time: 7 mins read
• Post category: Physics

Rutherford Atomic Model was proposed by Physicist Earnest Rutherford to explain the atomic model in 1911. Till that date, only J.J Thomson’s atomic model was known. J.J Thomson’s model was lacking experimental evidences. It also did not have any scientific explanation as well as not accepted widely.

Rutherford performed an experiment in 1911 to predict the closer structure to atom. The experiment carried by him is widely known as alpha(α) scattering experiment. The observation and conclusion drawn from his experiment are summarized as Rutherford atomic model.

Table of Contents

Rutherford Alpha Scattering Experiment

Alpha scattering experiment consists of a setup with a thin sheet of gold foil at the center, a radioactive source emitting α-particles and fluorescent screens. The α-particles emitting from radioactive source were allowed to pass through a sheet of thin gold foil. The fluorescent screens were used to detect the deflection of α-particles on striking the gold foil.

The source of α-particles was Radium(Ra), a radioactive substances. Radium was placed in a lead shield with a small opening to prevent from radiations during the experimental procedures.

The α-particles emitting from radioactive source were allowed to passed through the slit of the lead screen which hits the thin gold foil. On hitting the foil, alpha particles were deviated in different directions. The fluorescent screens were adjusted in such a way that deviated rays falls on it. With the help of microscope, fluorescent screens were studied.

Observation

Rutherford observe that majority of α-particles passed straight through the foil without deviation.

A few α-particles striking the gold foil were deflected through certain angles i.e. less than 90°.

A very few alpha(α) particles turned back towards the source after striking the foil i.e. -180°.

Conclusions

Majority of α-particles passed straight through the gold foil, Rutherford concluded that large part of an atom is empty or hollow.

Deflection of few particles at angle less than 90? concluded that negative(-ve) charge particles are revolving around the circular path, known as electrons.

A very few α-particles were deflected back towards the source. α-particles are beam of Helium nuclei. Since a very few of these particles are deflected back to its source, he concluded that small highly dense concentrated region exists at the center of atom.

The highly dense region with positive charge were called nucleus.

Read also: Bohr’s atomic model

Success of Rutherford Atomic Model

• It leads to the discovery of nucleus.
• Nucleus are positively charged & placed at the center of atom were conformed.
• This model is used for determining the closest distance of approach between positively charged particles and stationary nucleus.

Limitation & Drawback of Rutherford Model

This model could not explain atomic stability. According to Maxwell’s electromagnetic theory, a revolving electron should radiate energy continuously which makes electron to revolve in spiral path than in circular path. This results the electrons to finally fall into the nucleus which leads to the destruction of atoms.

Due to decrease in energy, the atom should give a continuous spectrum. But it failed to explain the formation of spectral lines.

FAQs on Rutherford Model

Rutherford atomic model is based on.

The main success of this model is, it led to the discovery of nucleus.

What are the success of Rutherford atomic model?

Which radioactive substance was used in α-scattering experiment.

Radium(Ra) is used as radioactive substance which was a source of α-particle.

What are the limitations of Rutherford model?

This model was not able to explain the stability of atom and also failed to explain the formation of spectral lines.

• https://en.wikipedia.org/wiki/Rutherford_model
• https://www.britannica.com/science/Rutherford-model
• https://byjus.com/chemistry/rutherfords-model-of-atoms-and-its-limitations/

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Rutherford’s Model of an Atom

We know a structure of an atom consists of electrons, protons, and neutrons . This was accurately presented after several scientists came up with different models. The classic model of an atom was given by Ernest Rutherford called the Rutherford atomic model or Rutherford model of the atom. However, it is not considered the accurate representation of an atom anymore. Let us know more about this model.

Suggested Video

Rutherford atomic model.

Rutherford proposed that an atom is composed of empty space mostly with electrons orbiting in a set , predictable paths around fixed, positively charged nucleus .

Rutherford’s Atomic Model (Source Credit: Britannica)

The concept of atom dates back to 400 BCE when Greek philosopher Democritus first conceived the idea. However, it was not until 1803 John Dalton proposed again the idea of the atom. But at that point of time, atoms were considered indivisible. This idea of an atom as indivisible particles continued until the year 1897 when British Physicist J.J. Thomson discovered negatively charged particles which were later named electrons.

To understand this concept in more detail you should read the Structure of Atom

He proposed a model on the basis of that where he explained electrons were embedded uniformly in a positively charged matrix. The model was named plum pudding model. However, J.J. Thomson’s plum pudding model had some limitations. It failed to explain certain experimental results related to the atomic structure of elements.

A British Physicist “Ernest Rutherford” proposed a model of the atomic structure known as Rutherford’s Model of Atoms. He conducted an experiment where he bombarded α-particles in a thin sheet of gold. In this experiment, he studied the trajectory of the α-particles after interaction with the thin sheet of gold.

You can download  Atom Cheat Sheet by clicking on the download button below

Browse more Topics under Structure Of Atom

• Introduction: Structure of Atom
• Atomic Number
• Bohr’s Model of Atom
• Charged Particles in Matter
• Mass Number
• Thomson’s Model of an Atom
• How are Electrons Distributed in Different Orbits (Shells)?
• Sub-Atomic Particles
• Atomic Models
• Shapes of Atomic Orbitals
• Energies of Orbitals
• Quantum Numbers
• Development Leading to Bohr’s Model of Atom
• Emission and Absorption Spectra
• Towards Quantum Mechanical Model of Atom

Rutherford Atomic Model Experiment

In Rutherford’s experiment, he bombarded high energy streams of α-particles on a thin gold foil of 100 nm thickness. The streams of α-particles were directed from a radioactive source. He conducted the experiment to study the deflection produced in the trajectory of α-particles after interaction with the thin sheet of gold. To study the deflection, he placed a screen made up of zinc sulfide around the gold foil. The observations made by Rutherford contradicted the plum pudding model given by J.J. Thomson .

Rutherford’s Gold Foil Experiment (Source Credit: Britannica)

Observations of Rutherford Model Experiment

On the basis of the observations made during the experiment, Rutherford concluded that

• Major space in an atom is empty – A large fraction of α-particles passed through the gold sheet without getting deflected. Therefore, the major part of an atom must be empty.
• The positive charge in an atom is not distributed uniformly and it is concentrated in a very small volume  – Few α-particles when bombarded were deflected by the gold sheet. They were deflected minutely and at very small angles. Therefore he made the above conclusion.
• Very few α-particles had deflected at large angles or deflected back. Moreover, very few particles had deflected at 180 o . Therefore, he concluded that the positively charged particles covered a small volume of an atom in comparison to the total volume of an atom.

What is the difference between the Thomsons and Rutherford Atomic model?

Postulates of Rutherford atomic model based on observations and conclusions

• An atom is composed of positively charged particles. Majority of the mass of an atom was concentrated in a very small region. This region of the atom was called as the nucleus of an atom. It was found out later that the very small and dense nucleus of an atom is composed of neutrons and protons.
• Atoms nucleus is surrounded by negatively charged particles called electrons . The electrons revolve around the nucleus in a fixed circular path at very high speed. These fixed circular paths were termed as “orbits.”
• An atom has no net charge or they are electrically neutral because electrons are negatively charged and the densely concentrated nucleus is positively charged. A strong electrostatic force of attractions holds together the nucleus and electrons.
• The size of the nucleus of an atom is very small in comparison to the total size of an atom.

Learn more about Thomsons Model of an Atom, by J.J. Thomsons , which was the first model of Atom.

Drawbacks of Rutherford Model

Limitations of Rutherford Atomic Model

Rutherford’s experiment was unable to explain certain things. They are:

• Rutherford’s model was unable to explain the stability of an atom. According to Rutherford’s postulate, electrons revolve at a very high speed around a nucleus of an atom in a fixed orbit. However, Maxwell explained accelerated charged particles release electromagnetic radiations . Therefore, electrons revolving around the nucleus will release electromagnetic radiation.
• The electromagnetic radiation will have energy from the electronic motion as a result of which the orbits will gradually shrink. Finally, the orbits will shrink and collapse in the nucleus of an atom. According to the calculations, if Maxwell’s explanation is followed Rutherford’s model will collapse with 10 -8 seconds. Therefore, Rutherford atomic model was not following Maxwell’s theory and it was unable to explain an atom’s stability.
• Rutherford’s theory was incomplete because it did not mention anything about the arrangement of electrons in the orbit. This was one of the major drawbacks of Rutherford atomic model.

Even though the early atomic models were inaccurate and could not explain the structure of atom and experimental results properly. But it formed the basis of the quantum mechanics and helped the future development of quantum mechanics.

Solved Questions for You

Question: Name the part of an atom discovered by Rutherford α-particles scattering experiment

Answer : The answer is 4. Rutherford α-particles scattering experiment led to the discovery of nucleus.

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Rutherford Atomic Model

Last updated at April 16, 2024 by Teachoo

As per Rutherford Nuclear Model of Atom ,

• Every atom has a nucleus .
• The size of the nucleus is very small . It is 1/10 the size of an atom .
• This nucleus is positively charged .
• Even though the nucleus is of small size, it has a very high mass . Nearly all the mass of an atom is inside the nucleus.
• Electrons revolve around the nucleus in a circular path .

How was the Rutherford Model formed?

• It was formed by the scientist Ernest Rutherford .

He designed the model after performing Alpha Particle Scattering Experiment on a gold foil .

What is an alpha particle?

• Alpha particles are nucleus of helium atoms . It has a charge of +2 . The fast moving alpha particles have a good amount of energy.
• The mass of an alpha - particle is 4u .

Why did Rutherford use a gold foil?

• He selected a gold foil because he wanted as thin a layer as possible . This gold foil was about 1000 atoms thick .

What did Rutherford expect before the experiment?

• Mass of the alpha particles was 4u while that of the proton is 1u. Hence, they were much heavier than the proton.
• Rutherford expected that alpha particles would deflect a little by the subatomic particles (protons and electrons) in the gold atoms.
• But since alpha particles were much heavier than protons , he did not expect to see large deflections.

What was Rutherford's Alpha Particle Scattering Experiment?

• In this experiment, Rutherford made fast moving alpha particles to fall on a gold foil .
• He observed that:
• Many of fast moving alpha particles pass straight through the gold foil with no deflection at all
• Some of the alpha particles were deflected by foil at small angles.
• Very less alpha particles(1 out of every 12000) were reflected back  at 180 degree (rebound)

Rutherford’s observations from his experiment: -

• Most of spaces inside atom was empty This is because most of the fast moving alpha particles pass straight through the gold foil.
• Positive charge of atom occupies very little space This is because only some of the alpha particles were deflected by the foil at small angles.
• All mass of atom and positive charged was concentrated in very small volume of atom called Nucleus This is because very less alpha particles were reflected back at 180 degree (rebound).

Note: From his experiment, he estimated that, radius of an atom is about 10 5   more than the radius of a nucleus.

What was Rutherford's model of an atom?

Rutherford's model of an atom stated that:

• There is a positively charged centre in an atom called the nucleus . Nearly all the mass of an atom resides in the nucleus .
• The electrons (negatively charged particles) revolve around the nucleus in circular paths.
• The size of the nucleus is very small as compared to the size of the atom .

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Rutherford Atomic Model

Rutherford Atomic Model was proposed by Ernest Rutherford in 1911. It is also called the Planetary Model of the Atom. It introduced the concept of a dense, positively charged nucleus at the center of an atom, with electrons orbiting around it, forming the basis for modern atomic theory.

In this article, we will learn about Rutherford’s Alpha Scattering Model, its observations, and limitations in detail.

According to Rutherford’s Atomic Model, the positively charged particles and the majority of the mass of an atom were said to be concentrated in a small volume. He referred to this area of the atoms as the nucleus . 

Another idea put forward by Rutherford’s model of an atom was that an atom’s nucleus should be surrounded by negatively charged electrons. Rutherford also suggested that the electrons circle the nucleus at the speed of light. He called these elliptical paths orbits.

Rutherford Gold Foil Experiment

To determine how electrons are arranged in an atom, the Alpha (α) Particle Scattering Experiment was organized by Rutherford. Rapidly moving α-particles were directed to bombard a thin sheet of gold.

• The gold foil was selected so as to obtain an extremely thin layer. The thickness of the gold foil was about 1000 atoms.
• Doubly-charged helium ions are known as α-particles. Rapidly moving α-particles possess a great deal of energy, as they have a mass of about 4 amu.

The hypothesis was that α-particles would be deflected by the sub-atomic particles in the gold atoms. Rutherford didn’t expect to witness significant deflections as the α-particles were considerably heavier than the protons. However, the experiment produced entirely unanticipated results.

Observations of Rutherford’s Gold Foil Experiment

Rutherford observed the following from his α-particle scattering experiment:

• A large percentage of alpha particles travelled through the gold film without being deflected, indicating that the majority of space in an atom is empty. As a result, an atom’s main portion must be empty.
• The positive charge in an atom is concentrated in a relatively small volume and is not dispersed evenly. When bombarded, the gold foil only deflected a small number of alpha particles. They experienced extremely slight angles of deflection. So he arrived at the stated conclusion.
• Very few alpha particles had deflected back or at large angles. In addition, relatively few particles had 180o deflected. As a result, he came to the conclusion that the positively charged particles only occupied a small portion of an atom’s overall volume.
• Alpha (α) Particle Scattering Experiment

Conclusion of Rutherford Gold Foil Experiment

Rutherford concluded the following from his observations:

• Because a large proportion of the α-particles directed toward the gold sheet went through it without any deflection, so, the majority of the space in an atom is vacant.
• Only a few α-particles were diverted off their route, suggesting that the atom’s positive charge takes up relatively little space.
• Since a very tiny percentage of α-particles completely rebounded, this implied that the atom’s mass and positive charge are concentrated in a small volume and not uniformly distributed.

Postulates of Rutherford Atomic Model 

Here are the major postulates of Rutherford’s atomic model based on observations and conclusions of the gold foil experiment:

• Positively charged particles make up an atom. The majority of an atom’s mass was contained in a very small area. The nucleus of an atom was the term used to describe this area of the atom. Later it was discovered that neutrons and protons make up the atom’s extremely tiny and dense nucleus.
• The electrons that surround an atom’s nucleus are negatively charged particles. The electrons rotate faster in a fixed circular path around the nucleus. Such a fixed circular path is called the orbit.
• Since electrons are negatively charged and the tightly packed nucleus is positively charged, an atom either has no net charge or is electrically neutral. The nucleus and electrons are held together by a strong electric force of attraction.

Drawbacks of Rutherford’s Model of Atom

There are several limitations or drawbacks of Rutherford’s atomic model, which are as follows:

Rutherford’s Model predicts that electrons will orbit around the positively charged nucleus, which is not anticipated to be stable. A charged particle in rapid motion along a circular route, would lose energy continually and eventually collapse into the nucleus. This causes an atom to be unstable, whereas we know that atoms are extremely stable.

• Because it merely postulated the existence of protons in the nucleus, the Rutherford Model could not resolve the problem of atomic mass.
• Rutherford’s Atomic Model doesn’t explain the arrangement of electrons in the atom, which makes this model incomplete in this regard.

Also, Read :

• Atomic Structure
• Thomson’s Atomic Model 
• Bohr’s Model of an Atom

FAQs on Rutherford’s Atomic Model

Why was j.j. thomson’s atomic model flawed.

Thomson’s atomic model does not explain how the positive charge on the electrons inside the atom is maintained. It also fails to explain the stability of an atom. The nucleus of an atom is not mentioned in the hypothesis. It could not explain Rutherford’s scattering experiment.

What is Rutherford’s Scattering Experiment?

To determine how electrons are arranged in an atom, the Alpha (α) Particle Scattering Experiment was organized by Rutherford. Rapidly-moving α-particles were directed to bombard a thin sheet of gold. The gold foil was selected so as to obtain an extremely thin layer. The hypothesis was that α-particles would be deflected by the sub-atomic particles in the gold atoms. Rutherford didn’t expect to witness significant deflections as the α-particles were considerably heavier than the protons. However, the experiment produced entirely unanticipated results.

Which sub-atomic particle was discovered by Rutherford through his Alpha Particle Scattering Experiment?

The discovery of the proton was made by Rutherford in 1917, using his alpha particle scattering experiment as a base. Also, he discovered the nucleus of the atom with his experiment in 1911.

Why was a gold foil used in the Alpha Particle Scattering Experiment?

A gold foil was selected so as to obtain an extremely thin layer and as it is the most malleable metal. However, if any other metal foil was used, the results obtained would be inconsistent.

What was the main drawback of Rutherford’s Model of Atom?

By which angles did the α -particles get deflected in the scattering experiment.

The majority of the fast-moving α-particles went directly through the gold foil. The foil deflected some of the α-particles by fairly small angles. Only a few α-particles were completely deflected back (by 180 degrees).

How did Rutherford define an Orbit?

According to Rutherford, negatively charged electrons encircle the nucleus of an atom. He believed that the electrons encircling the nucleus travel around it in circular routes at great speeds. He referred to these circular routes as well-defined orbits.

Who discovered Atomic Nucleus?

Ernest Rutherford concluded that the majority of the mass of the atom is condensed at the center of the atom, which was named the nucleus.

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