Isobars are atoms of different chemical elements that have the same mass number (number of nucleons, which is the sum of protons and neutrons) but different atomic numbers (number of protons). Here are 10 examples of isobar pairs/groups:
Examples of Isobars
The following table provides 10 examples of isobar pairs or groups, showing the elements, their atomic numbers (Z), and their shared mass number (A):
| Example | Element 1 (Z) | Element 2 (Z) | Element 3 (Z) | Mass Number (A) |
|---|---|---|---|---|
| 1 | 40K (19) | 40Ar (18) | 40Ca (20) | 40 |
| 2 | 3H (1) | 3He (2) | 3 | |
| 3 | 14C (6) | 14N (7) | 14 | |
| 4 | 124Sn (50) | 124Te (52) | 124 | |
| 5 | 58Fe (26) | 58Ni (28) | 58 | |
| 6 | 131I (53) | 131Xe (54) | 131 | |
| 7 | 87Br (35) | 87Kr (36) | 87 | |
| 8 | 80Ge (32) | 80Se (34) | 80 | |
| 9 | 113Cd (48) | 113In (49) | 113 | |
| 10 | 234Th (90) | 234Pa (91) | 234U (92) | 234 |
In each of these examples, the listed atoms have the same number of nucleons (protons + neutrons) but differ in the number of protons, meaning they represent different elements. This difference in proton number is what defines them as different elements, even though they share the same mass number.
