CBSE Class 9 Answered

Subatomic particle is also called elementary particle.

Subatomic particles are various self-contained units of matter or energy that are the fundamental constituents of all matter.

Subatomic particles include, 

1.      The negatively charged electrons which are almost massless particles that nevertheless account for most of the size of the atom.

2.      The positively charged protons which are heavier building blocks of the small but very dense nucleus of the atom.