Give the number of protons and the number of neutrons in the nucleus of each ofthe following isotopes: (a) Aluminum-25 (b) Technetium-95 (c) Tin-120 (d) Mercury-200

Answer: (a) Aluminium-Al has 12 protons and 13neutrons (b) Technetium-Tc has 43 protons and 52neutrons (c) Tin-Sn has 50protons and 70 neutrons (d) Mercury - Hg has 80protons and 120neutrons

Explanation:

All elements on the periodic table are are arranged in terms of atomic number.

For a neutral atom (uncharged atom), atomic number is the same as proton number. And the sum of number of proton and number of neutrons gives mass number.

Isotopes exist as a result of difference in mass number of atoms but the same atomic number, which implies isotopes of an element always have the same number of protons but different neutron numbers.

(a) Aluminum-25 has a mass number of 25 with atomic number of 12.

Since its a neutral atom, number of protons is 12 while neutron number can be deduced as,

Mass number = neutron number + proton number

Neutron numbers = mass number - proton number

Neutron number = 25-12=13neutrons

(b) Technetium - 95 has a mass number of 95 with atomic number of 43.

Since its a neutral atom, number of protons is 12 while neutron number can be deduced as,

Mass number = neutron number + proton number

Neutron numbers = mass number - proton number

Neutron number = 95-43=52neutrons

(c) Tin-120 has a mass number of 120 with atomic number of 50

Since its a neutral atom, number of protons is 50 while neutron number can be deduced as,

Mass number = neutron number + proton number

Neutron numbers = mass number - proton number

Neutron number = 120-50=70neutrons

(d) Mecury-200 has a mass number of 200 with atomic number of 80.

Since its a neutral atom, number of protons is 80 while neutron number can be deduced as,

Mass number = neutron number + proton number

Neutron numbers = mass number - proton number

Neutron number = 200-80=120neutrons