Periodic Properties Test - 11

Both Be⁺² ion and Al⁺³ ion have the same charge density and the same polarising power; hence, both show resemblance in their chemical behaviour.

Group 2 elements invariably exhibit an oxidation state of +2 in their compounds.
Group 14 elements form stable compounds in both +2 and +4 oxidation states.

In the group 14, Ge, Sn and Pb have a lesser tendency to show the +4 oxidation state due to the inert pair effect.

In the s-block elements, the last electron enters the s-subshell of the outermost shell.
The valence shell electronic configuration of the group 2 elements is: ns².
In the d-block elements, the last electron enters the d-subshell of the (n - 1) shell, but the outermost electron is in the ns orbital.
The valence shell electronic configuration of the group 3 elements is: (n - 1)d¹ ns².

The given electronic configuration is that of the f-block elements, i.e. lanthanides and actinides.

Though all the given anions are unstable, however Be^- is the least stable anion as the gain of one electron disturbs the stable configuration of fully-filled 2s orbital.

Due to the ineffective shielding of the d-electrons in the 4^th and 5^th shells and of the d- and f-electrons in the 6^th shell, there is a fluctuation in the trend of atomic radii and consequently the ionisation potentials.

Ionisation potential of the elements is directly proportional to the effective nuclear charge and inversely proportional to the atomic radii.
The ionisation energy is high if the removal of the electron disturbs a stable electronic configuration.

The value of electron affinity decreases down the group because the atomic size increases and the effective nuclear charge decreases.
However, the electron affinity of F is less than that of chlorine because owing to its small size, electronic repulsions come into play on the gain of an electron.