Question

Bohr models of two atoms are given (symbols are not real).
(a) What is the atomic number of atom A?
(b) Write the sub-shell electronic configuration of atom B.
(c) Suppose the electron in each atom is to be removed, which one may need higher ionisation energy? Give reason.

Answer 1

(a) Atomic number of atom A = 11
(b) The sub-shell electronic configuration of atom B is as follows
$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$
(c) Atom A will require higher ionisation energy because-
i. As the atomic size increases, the ionization potential decreases because as the atomic size increases, the effective nuclear attraction experienced by the outermost electron decreases.
ii. In atom A, the outermost belongs to the third orbital and in atom B, the outermost electron belongs to the fourth orbital. Thus, the atomic size of the atom B is greater than the atomic size of the atom A.
iii. Hence, atom B will require less ionization energy to remove loosely held outermost electron while atom A will require more ionization energy to remove tightly held outermost electron