Question

(a) What is meant by (i) a group, and (ii) a period, in a periodic table?
(b) How many periods and groups are there in the long form of periodic table?
(c) Give two examples each of (i) group 1 elements (ii) group 17 elements (iii) group 18 elements.

Answer 1

(a) (i) A group is a vertical column of elements in a periodic table.
(ii) A period is a horizontal row of elements in a periodic table.

(b) There are seven periods and eighteen groups in the long form of the periodic table.

(c) (i) Lithium (Li) and sodium (Na) are two elements of group 1.
(ii) Chlorine (Cl) and bromine (Br) are two elements of group 17.
(iii) Neon (Ne) and argon (Ar) are two elements of group 18.