Bohr models of atoms A, B, C, D are given (Symbols are not real).

a) Write the atomic number, mass number and electronic configuration of the atoms,

b) Among these, which are isotxopes? Why?

a.

Here number of protons = the number of electrons = 6

Since, atomic number of an atom = the number of protons

Hence the atomic number of the atom = 6

We know that mass number = number of protons + number of neutrons

∴ Mass number = 6 + 6 =12

Electronic configuration of the atom : -

K shell - 2 electrons

L shell – 4 electrons

Here number of protons = the number of electrons = 7

Since, atomic number of an atom = the number of protons

Hence the atomic number of the atom = 7

We know that mass number = number of protons + number of neutrons

∴ Mass number = 7 + 8 =15

Electronic configuration of the atom : -

K shell - 2 electrons

L shell – 5 electrons

Here number of protons = the number of electrons = 6

Since, atomic number of an atom = the number of protons

Hence the atomic number of the atom = 6

We know that mass number = number of protons + number of neutrons

∴ Mass number = 6 + 8 =14

Electronic configuration of the atom : -

K shell - 2 electrons

L shell – 4 electrons

Here number of protons = the number of electrons = 8

Since, atomic number of an atom = the number of protons

Hence the atomic number of the atom = 8

We know that mass number = number of protons + number of neutrons

∴ Mass number = 8 + 8 =16

Electronic configuration of the atom: -

K shell - 2 electrons

L shell – 6 electrons

b). Isotopes – These are the chemical species having the same atomic number but different mass numbers.

In the above given atoms A and C have the same atomic number and differ only in the matter of number of neutrons present in their respective nucleus.

Hence, atom A and C are isotopes.