Rutherford Atomic Model [SSC][HSC]: Experiment, Observations And Limitations

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Rutherford's gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus. Based on these results, Rutherford proposed the nuclear model of the atom.
The Geiger–Marsden experiments (also called the Rutherford gold foil experiment) were a landmark series of experiments by which scientists learned that every atom has a nucleus where all of its positive charge and most of its mass is concentrated.

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.

Physicist Ernest Rutherford established the nuclear theory of the atom with his gold-foil experiment. When he shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected. He concluded that a tiny, dense nucleus was causing the deflections.

Many physicists distrusted the Rutherford atomic model because it was difficult to reconcile with the chemical behavior of atoms. The model suggested that the charge on the nucleus was the most important characteristic of the atom, determining its structure. On the other hand, Mendeleyev’s periodic table of the elements had been organized according to the atomic masses of the elements, implying that the mass was responsible for the structure and chemical behavior of atoms.
A month after Rutherford's paper appeared, the proposal regarding the exact identity of atomic number and the nuclear charge was made by Antonius van den Broek, and later confirmed experimentally within two years, by Henry Moseley.

These are the key indicators-
The atom's electron cloud does not influence alpha particle scattering.

Much of an atom's positive charge is concentrated in a relatively tiny volume at the center of the atom, known today as the nucleus. The magnitude of this charge is proportional to (up to a charge number that can be approximately half of) the atom's atomic mass—the remaining mass is now known to be mostly attributed to neutrons. This concentrated central mass and charge are responsible for deflecting both alpha and beta particles.

The mass of heavy atoms such as gold is mostly concentrated in the central charge region since calculations show it is not deflected or moved by the high-speed alpha particles, which have very high momentum in comparison to electrons, but not with regard to a heavy atom as a whole.

The atom itself is about 100,000 times the diameter of the nucleus.

Contribution to modern science

This could be related to putting a grain of sand in the middle of a football field.
After Rutherford's discovery, scientists started to realize that the atom is not ultimately a single particle, but is made up of far smaller subatomic particles. Subsequent research determined the exact atomic structure which led to Rutherford's gold foil experiment. Scientists eventually discovered that atoms have a positively charged nucleus (with an exact atomic number of charges) in the center, with a radius of about 1.2 × 10−15 meters × [atomic mass number]1⁄3. Electrons were found to be even smaller.

Later, scientists found the expected number of electrons (the same as the atomic number) in an atom by using X-rays. When an X-ray passes through an atom, some of it is scattered, while the rest passes through the atom. Since the X-ray loses its intensity primarily due to scattering at electrons, by noting the rate of decrease in X-ray intensity, the number of electrons contained in an atom can be accurately estimated.

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YouTube url:	https://youtu.be/MBS0vRMcFY0
Created:	29. 1. 2021 13:51:47

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Rutherford Atomic Model [SSC][HSC]: Experiment, Observations And Limitations