Which of the three subatomic particles is responsible for determining the reactivity of an element?

The three subatomic particles are the electron, proton and neutron

Explanation:

There are three subatomic particles in an element which are responsible to determine their reactivity are called as electrons, protons and neutrons. These three particles have different charges associated with them like electron are negatively charged,  protons are positively charged and neutrons are neutrally charged  (i.e) no net electric charge is associated with them. The nucleus is the center of the atom.