Question

Define isobar. Give an example.

Answer 1

Hint: As we know that the atoms which have the same number of nucleons (nucleons are the species present inside the nucleus of the atom). In simple words we can say that isobars are the different chemical elements which have different atomic numbers but have the same mass number. So here we have to explain isobar along with an example.

Complete answer:
Let us discuss the concept of isobars as follows:-
-Isobars: These are the atoms that have the same number of nucleons (nucleons are the species present inside the nucleus of the atom) or we can say that these are the different chemical elements which have different atomic numbers but have the same mass number.
-In 1918, Alfred Walter Stewart suggested the term isobar that is derived from the Greek word where ‘isos’ means equal and ‘baros’ means weight.
-These isobaric elements or species have different chemical properties as there is a difference in electron count. The isobars have the same atomic mass but different atomic numbers because the number of neutrons are different that add up with protons to make the total count of nucleons same and hence they have the same atomic mass.
-The example of isobar is given as follows:-
 $_{18}A{{r}^{40}}{{,}_{19}}{{K}^{40}}an{{d}_{20}}C{{a}^{40}}$ are the isobars of each other as the atomic mass (or the number of nucleons) of each of them is 40 which is written in the superscript and their atomic number is different which is shown in the subscript. As their atomic numbers are different therefore their chemical properties are also quite different from each other.

Note:
-Remember that isotopes and isobars are completely different categories of elements as isotopes are the elements which have the same atomic number but different mass number whereas isobars are the elements which have different atomic number and same mass number.