Atomic Structure and Radioactivity - SS1 Physics Past Questions and Answers - page 2

Protons are subatomic particles with a positive charge (+1) and are located in the nucleus of an atom. They contribute to the mass of the atom and determine the atomic number of an element. Neutrons are subatomic particles with no charge (neutral) and are also found in the nucleus. They contribute to the mass of the atom without affecting the atomic number. Electrons are subatomic particles with a negative charge (-1) and orbit around the nucleus in energy levels or electron shells. They are much lighter than protons and neutrons and are involved in chemical reactions and bonding.

Protons determine the identity of an element. Each element has a unique number of protons in its nucleus, which is known as the atomic number. The atomic number distinguishes one element from another. For example, hydrogen has one proton, helium has two protons, and so on. The number of protons determines the element's properties and its position in the periodic table.