Question

Among the elements B, Al, C and Si

(a) Which has the highest first ionization enthalpy?

(b) Which has the most negative electron gain enthalpy?

(c) Which has the largest atomic radius?

(d) Which has the most metallic character?

Answer 1

a). The highest first ionisation enthalpy is seen in carbon as it is non metal which generally have higher I.E as they are electronegative in nature and also it is tetra covalent due to which the release of any electron is very difficult from its excited state.
b). Similarly carbon has the most negative electron gain enthalpy as it will require an extra energy to add an electron and hence it will have maximum negative value of electron gain enthalpy.
c).The largest atomic radius will be found in aluminium (Al) as it is the metal of second group whose metallic character is larger than silicon and so it has larger radius. (Atomic radius increases down the group.)
d).The most metallic character is found in Aluminium.