Can you please help me with the following questions. Thanks!

How does Rutherford's model of the atom acoount for the back-scattering of alpha particles directed at the gold leaf?

What is Bohr's key idea (involving matter waves) that makes the Bohr atom have discrete engergy levels?

The very high positive charge at the center will stop and repel any incoming positive charges.

Bohr having matter wave thoughts? Must be a new revision of history. Bohr key premise was that electrons occupied only allowed levels, he could not explain why.

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Of course! I can help you with both questions. Let's start with Rutherford's model of the atom.

Rutherford's model of the atom, also known as the planetary model, proposes that the atom consists of a small, dense, positively charged nucleus surrounded by negatively charged electrons in orbit around it. In this model, most of the atom's mass and positive charge is concentrated in the nucleus.

To understand how Rutherford's model accounts for the back-scattering of alpha particles directed at the gold leaf, we need to consider the experiment known as the "Rutherford scattering experiment."

In this experiment, alpha particles (which are positively charged) were directed at a thin gold foil. According to the prevailing Thomson's model of the atom, these alpha particles should have passed straight through the foil with minor deflections due to the uniformly distributed positive charge in the atom.

However, Rutherford's experiment showed that some of these alpha particles were deflected at large angles, and a few even bounced back in the opposite direction. This unexpected observation led to Rutherford proposing his new model.

Rutherford's model suggests that since some alpha particles were being deflected, the positive charge in the atom must be concentrated in a small region, which he called the nucleus. The majority of the alpha particles passed through the gold leaf because the atom itself is primarily empty space. However, some of them experienced close encounters with the positively charged nucleus, resulting in large deflections or even back-scattering.

So, in summary, Rutherford's model accounted for the back-scattering of alpha particles by proposing that the positive charge in the atom is concentrated in a small, dense nucleus.

Now let's move on to Bohr's atom and its discrete energy levels.

Bohr's model of the atom is an extension of Rutherford's model and is based on the idea that electrons move in discrete, quantized orbits around the nucleus. Bohr's key idea involves matter waves and the concept of quantization of angular momentum.

According to classical physics, electrons orbit the nucleus in a continuous manner, similar to planets orbiting the sun. However, this classical view couldn't explain why electrons do not spiral into the nucleus due to the electromagnetic radiation they emit.

Bohr's key idea was to propose that electrons can only exist in certain stable orbits called "stationary states" or "energy levels." These energy levels have specific energies associated with them. The electron can jump between these energy levels by absorbing or emitting energy in discrete amounts.

Bohr suggested that electrons possess both particle-like and wave-like properties, similar to light. He proposed that the angular momentum of an electron is quantized, meaning it can only have certain specific values. This quantization leads to the existence of discrete energy levels for electrons in an atom.

In other words, Bohr's idea was that electrons can only occupy specific orbits with specific energies. Electrons in the lowest possible energy level, also known as the ground state, are the most stable. When an electron absorbs energy, it jumps to a higher energy level or an excited state. However, it cannot stay in the excited state indefinitely and eventually returns to a lower energy level by emitting energy in the form of light or other radiation.

So, Bohr's key idea involving matter waves and the quantization of angular momentum explains why the Bohr atom has discrete energy levels.

I hope this helps explain both concepts to you! If you have any more questions, feel free to ask.