The only subatomic particle directly involved in chemical reactions between atoms is the electron.

Here's why:

* Electrons occupy the outermost energy levels (shells) of atoms. These shells are where interactions with other atoms occur.

* Chemical bonds are formed by the sharing or transfer of electrons. This process is called "bonding."

* Electrons are much lighter than protons and neutrons. This makes them more easily moved or shared during chemical reactions.

While protons and neutrons are essential for the identity and stability of an atom, they remain in the atom's nucleus and don't directly participate in chemical bond formation.