Question

(a) Explain why:
(i) All the elements of a group have similar chemical properties.
(ii) All the elements of a period have different chemical properties.

(b) The atomic radii of three elements X, Y and Z of a period of the periodic table are 186 pm; 104 pm and 143 pm respectively. Giving a reason, arrange these elements in the increasing order of atomic numbers in the period.

Answer 1

(a) (i) All the elements of a group have similar chemical properties because they have the same number of electrons in their outer most shell.
(ii) All the elements of a period have different chemical properties because the number of valence electrons for each varies.

(b) The elements in the increasing order of atomic numbers in the period is X