What is meant by the terms :

(i) subatomic particles,

(ii) nucleus,

(iii) orbits,

(iv) atomic number

(v) mass number with reference to an atom.

(i) Subatomic particles : The particles into which an atom is divided (i.e., protons, electrons, neutrons) are called the subatomic particles.

(ii) Nucleus : The centre or the nucleus of the atom is the place where the protons and neutrons are found.

(iii) Orbits : The electrons revolve around the nucleus along imaginary paths known as shells or more accurately orbits or orbitals.

(iv) Atomic number : Number of protons or number of electrons present in an atom. [Z]

(v) Mass number [A] : The Mass number of an atom is the total number of protons and neutrons collectively called nucleons in the nucleus of the atom.