How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move:

(a) Down a group and

(b) From left to right in a period

The modern periodic table consists of 18 groups and 7 periods.

i) Down the group, the atomic size and metallic character of elements increase.

ii) On moving from left to right in a period, the atomic size and metallic character of elements decreases.