i.
Atomic
size is determined by using atomic radius.
ii.
For
an isolated atom, its atomic radius is the distance between the centre of the
atom (i.e. centre of its nucleus) and its outermost shell.
iii.
In
a period, atomic radius generally decreases from left to right. This is because
the electrons are added to same shell and experience greater pull from the
nucleus.
iv.
Atomic
radius increases in a group from top to bottom as new shells are added bringing
outermost electrons farther from the nucleus.
