Isotopes, Isobars and Isotones

Isotopes :-

These are atoms of the same elements having same atomic number but different mass number and neutrons number.

Examples –

₁H¹, ₁H² and ₁H³

(protium) (deuterium) (tritium) are the Isotopes of hydrogen.

Here deuterium oxide to form heavy water.

Note – Tritium nuclei being unstable, do not occur naturally and are produced artificially in laboratories.

Other examples –

Oxygen → ₈O¹⁶ , ₈O¹⁷ and ₈O¹⁸

Chlorine → ₁₇Cl³⁵ and ₁₇Cl³⁷

Neon → ₁₀Ne²⁰ and ₁₀Ne²²

Carbon → ₆C¹² , ₆C¹³ and ₁₄C¹⁴

• The element gold (Au) has 32 isotopes ranging from A = 173 to A = 204

• As the atoms of isotopes have identical electronic structure, They have identical chemical properties and placed it in the same location in the periodic table.

Isobars :-

Isobars are atoms of different elements having the same mass number ‘A’ but different atomic number ‘Z’

Examples – The nuclei ₈O¹⁶ and ₇N¹⁶ represent two isobars.

Since Isobars are atoms of different elements, they have different physical and chemical properties.

Other examples –

₁H³ and He³

₇N¹⁴ and C¹⁴

₈O¹⁷ and F¹⁷

Isotones :-

These are atoms of different elements having the same number of neutrons (n).

Examples –

₆C¹⁴ and ₈O¹⁶

n = A – Z n = A – Z

= 14 – 6 = 16 – 8

= 8 = 8

₃Li⁷ and ₄Be⁸

n = A – Z n = A – Z

= 7 – 3 = 8 – 4

= 4 = 4

¹H³ and ₂He⁴

n = A – Z n = A – Z

= 3 – 1 = 4 – 2

= 2 = 2