The composition of the nuclei of three atomic species X, Y, and Z are given as follows. Class 9

The composition of the nuclei of three atomic species X, Y, and Z are given as follows. Class 9

Question 1.

The composition of the nuclei of three atomic species X, Y, and Z are given as follows.

Explain the relation between the following:

(i) Y and Z

(ii) Z and X

Answer:

First, let us find the mass numbers:

1. X: protons = 18, neutrons = 19, mass number = 18+ 19 = 37
2. Y: protons = 17, neutrons = 18, mass number = 17 + 18 = 35
3. Z: protons =17, neutrons = 20, mass number = 17 + 20 = 37

(i) Y and Z: Both Y and Z have the same number of protons (atomic number = 17), which means they belong to the same element - Chlorine (Cl). However, they have different mass numbers (Y = 35, Z = 37). Therefore, Y and Z are isotopes of each other. They are atoms of the same element with the same atomic number but different mass numbers.

(ii) Z and X: Z has atomic number = 17 (Chlorine) and X has atomic number = 18 (Argon). They are different elements. However, both Z and X have the same mass number = 37. Atoms of different elements that have the same mass number but different atomic numbers are called isobars. Therefore, Z and X are isobars.