Atomic & Nuclear Physics

Atomic Physics

Atom is the smallest part of matter which takes part in chemical reactions. Atoms of the same element are similar in mass, size and characteristics. Atom consists of three fundamental particles electron, proton and neutron. All the protons and neutrons are present election, proton and neutron. All the protons and neutrons are presents in the central core of atom called nucleus. Electrons revolve around the nucleus.

In an atom, electrons and protons are equal in number and have equal and opposite charge. Hence atom is neutral.

Properties of fundamental Particles

Particle	Mass (kg)	Charge (coulomb)	Discoverer
Proton	1.672 x 10⁻²⁷	-1.6 x 10⁻¹⁹	Rutherford
Neutron	1.675 x 10⁻²⁷	0	Chadwick
Electron	9.108 x 10⁻³¹	-1.6 x 10⁻¹⁹	J.J. Thomson

Note: Proton was discovered by Golastin and named by Rutherford.

Till today, several subatomic particles have been discoved. Some important of them are as follows.

Particle	Mass (kg)	Charge	Discoverer
Positron	9.108 x 10⁻³¹	+1.6 x 10 ⁻¹⁹	Anderson	Antiparticle of electron
Neutrino	0	0	Pauli
Pi-meson	274 times the mass of electron	Positive and negative both	Yakawa	Unstable
Photon	0	0		Velocity equal to that of light.