Question

Give one example of isobars.

Answer 1

Hint: Isobars are chemical elements that have the same mass number but different atomic number. That is, they have different numbers of protons in the nucleus but the sum of protons and neutrons in the nucleus is the same. Protons and neutrons are often together termed as nucleons, since they reside inside the nucleus.

Complete step by step answer:
Sometimes elements have different atomic numbers but the same mass number. This means that the number of protons in their nucleus is different but the sum of the protons and neutrons in their nucleus is the same.
Such elements are known as isobars.
Some examples of isobars are ( $_{18}^{40}Ar$, $_{19}^{40}K$, $_{20}^{40}Ca$) and ($_{6}^{14}C$,$_{7}^{14}N$).

Additional information:
Sometimes an element may have the same atomic number but different mass number. That is the number of protons are the same but the sum of protons and neutrons are not the same due to a difference in the number of the neutrons. These are known as the isotopes of the element. Some examples of isotopes are ( $_{1}^{1}H$,$_{1}^{2}H$,$_{1}^{3}H$ ) and ($_{6}^{12}C$,$_{6}^{14}C$).
Elements can also have different atomic numbers, that is, different numbers of protons but the same number of neutrons. Such elements are known as isotones. Some examples of isotones are ($_{19}^{39}K$,$_{20}^{40}Ca$, because they both contain 20 neutrons in their nucleus).

Note: It is imperative that students have a good hold of the periodic table and have it memorized through the use of some clever mnemonics. Such types of problems and many others are based upon the concept of the periodic table and it will become almost impossible for a student to attempt the question if he does not have the periodic table in mind.
A very common mistake of students is to get confused between isotopes and isobars because the concepts are quite similar in nature. However, students should try to keep the difference between the two in mind.