Why do the number of subatomic particles determines the properties/characteristics of an element?

Subatomic particles are the building blocks of the element.

Explanation:

The elements are nothing but, structures that are made up of the same atom. For example, element sodium has sodium atoms. These atoms are in turn made up of three subatomic particles namely proton, electron and neutron.

The nucleus of the atom is composed of positively charged protons and neutrally charged neutron whereas the negatively charged electron is seen revolving around the nucleus.

As the entire structure of the atom is dependent upon the subatomic particles, it is inferred that the character of the element is determined by the subatomic particles.