Question

Explain with examples:
(i) Atomic number (ii) Mass number,
(iii) Isotopes and (iv) Isobars.
Give any two uses of isotopes.

Answer 1

(i) Atomic number: The atomic number of an element is equal to the number of protons in the nucleus of its atom.
e.g., Oxygen has 6 protons hence atomic no. = 6.
(ii) Maas number: The mass number of an atom is equal to the number of protons and neutrons in its nucleus.
Nucleons = number of protons + number of neutrons
Example: Protons + Neutrons = Nucleus = Mass number
6 + 6 = 12iii)Isotopes: Isotopes are atoms of the same element which have different mass number but same atomic number.

(iv)Isobars: Isobars are atoms having the same mass number but riifteren atomic numbers.

Both calcium and argon have same mass number but different storm number.
Two uses of isotopes are:
(i) An isotope of iodine is used in the treatment of goitre.
(ii) An isotope of uranium is used as a fuel in nuclear reactors.