Question

Name the three subatomic particles of an atom.

Answer 1

Hint: Particles that are smaller than the atom are called subatomic particles. It is also called the fundamental particle of the atom. One of them is positively charged, one is negatively charged and the last one has no charge.

Complete Solution :
In 1897, J.J Thomson found out electrons as a constituent of atoms. He concluded that an electron consists of a negative charge and had very small mass when compared to that of the atom. Since an atom was discovered to be electrically neutral it was concluded that some source of positive charge must be available in the atom. This preferably led to the experimental discovery of the proton, which became the positively charged subatomic particle. Proton was found approximately 1840 times heavier than an electron. Additional experiments disclosed that the atomic masses were much more than that expected from the presence of just protons and electrons in the atom. This advocated the presence of neutral particles with mass analogous to that of protons in the atom. Sir James Chadwick found out this neutral particle and called it neutron afterwards in 1932.
- Thus we may conclude that atoms are not indivisible but are made up of three fundamental particles i.e. electron proton and neutron.

Note: The fundamental particles of atoms and their characteristics are given in the table.

Particle	Symbol	Mass/Kg	Actual Charge/C	Relative Charge
Electron	e	$9.109\text{x1}{{\text{0}}^{-31}}$	$-1.602\text{x1}{{\text{0}}^{-19}}$	-1
Proton	p	$1.672\text{x1}{{\text{0}}^{-27}}$	$1.602\text{x1}{{\text{0}}^{-19}}$	+1
Neutron	n	$1.674\text{x1}{{\text{0}}^{-27}}$	0	0