Question

Explain the Physics of the atom.

Answer 1

Construct a model of the atom:

Any attempt to construct a model of the atom must start from two experimental facts.

1. First, the atom is electrically neutral.
2. Second, it appears to contain electrons that are negatively charged as well as relatively light in mass compared with the atom itself (the word ‘appears’ must be included because the fact that an electron is emitted by an atom doesn’t necessarily mean that it exists in its free-space form inside the atom).
3. The picture of the atom has changed or evolved as new experimental clues as well as mathematical theories have been pieced together.

Structure of Atom:

1. An atom consists of subatomic particles like electrons, protons, and neutrons.
2. Protons and neutrons are the subatomic particles that constitute the central nucleus of an atom.
3. Protons are electrically positive particles.
4. Neutrons are electrically neutral particles.
5. Electrons are electrically negative particles that revolve around the nucleus in fixed stationary orbits.
6. To remain electrically neutral, a stable atom generally contains an equal number of protons and electrons (equal positive and negative charge).
7. Hence, the number of protons represents the atomic number of an atom while the total number of protons and neutrons represents the mass number of an atom.
8. Since electrons appear on the shells of an atom, they are generally responsible for participating in various chemical reactions.
9. This model is also known as Bohr's model of an atom.

Bohr's Postulates:

1. Electrons in atoms orbit the nucleus.
2. An atom can exist only in certain specific energy states, in which an electron can reside without the emission of radiant energy.
3. Transmission between stationary states can occur only by jumping from one allowed orbit to another, and this process produces/absorbs only a discrete quantum of electromagnetic radiation.
4. The angular momentum of a stationary electron is also quantized.