What are Isobars?

Definition of Isobar

Isobars are defined as

The atoms that have same number of nucleons. Isobars of different chemical elements have different atomic number but have the same mass number.

Alfred Walter Stewart in 1918 suggested the term isobars. It is derived from the Greek word in which isos means equal and baros means weight.

Example of Isobar

Argon, potassium, and calcium having atoms of the same mass number 40.

₁₈Ar⁴⁰, ₁₉K⁴⁰, ₂₀Ca⁴⁰ where 18, 19 and 20 shown as subscripts are the atomic numbers of the three elements respectively are isobars. Since the atomic numbers are different their chemical properties are also different. The structure of argon, potassium, and calcium are given below.