The atom is the smallest particle of an element that take part in a chemical reaction. The atom is made up of three subatomic particles:
Protons
Electrons
Neutrons
(i) Protons
The proton is positively charged
Is found in the centre of an atom called nucleus
It has a relative mass 1
The number of protons in a atom of an element is its Atomic number
(ii) Electrons
The Electrons is negatively charged.
Is found in fixed regions surrounding the centre of an atom called energy levels/orbitals.
It has a relative mass 1/1840.
The number of protons and electrons in a atom of an element is always equal.
(iii)Neutrons
The Neutron is neither positively or negatively charged thus neutral.
Like protons it is found in the centre of an atom called nucleus.
It has a relative mass 1.
The number of protons and neutrons in a atom of an element is its Mass number.