Atomic structure

What is the key structure of the atomic nucleus?

The nucleus is:

1. Very small compared to the whole atom.

2. Highly dense, containing almost all the atom’s mass.

3. Positively charged due to protons.

What was the significance of the gold foil experiment?

It showed that atoms have a small, dense, positively charged nucleus, surrounded by mostly empty space.

What is the Bohr model of the atom?

The Bohr model describes electrons orbiting the nucleus in fixed energy levels or shells.

What are subatomic particles?

The three main subatomic particles are:

• Proton: Positively charged, in the nucleus.

• Neutron: No charge, in the nucleus.

• Electron: Negatively charged, outside the nucleus.

What is the atomic number (Z)?

The number of protons in an atom. It also equals the number of electrons in a neutral atom.

What is the mass number (A)?

The total number of protons and neutrons in an atom.

Why is the electron’s mass ignored in calculations?

The electron has an extremely small mass compared to protons and neutrons.

What are isotopes?

Isotopes are atoms of the same element with different numbers of neutrons.

Give an example of an isotope

Carbon-12 and Carbon-14 are isotopes of carbon.

What are radioactive isotopes (radioisotopes)?

Unstable isotopes that release radiation as they decay to become more stable.

How are radioisotopes used in medicine?

They are used in imaging tests and cancer treatments.

What is Uranium nitrate (uranyl)?

A radioactive compound containing uranium, used in early radioactivity research.