Isobars are the atoms of different elements which have the same atomic weight, but different atomic numbers. Isobars contain different number of protons, different number of electrons and also different number of neutrons. Only the total number of nucleons in them is the same.
For example 11Na22 and 10Ne22 are isobars. Similarly, 20Ca40 and 18Ar40 are isobars 17C137 and 16S37 are also isobars. The chemical properties of isobars are widely different. Their physical properties may be identical. Isobars occupy different places in the periodic table.
