The atomic size or radius is defined as the distance between the nucleus and the outermost shell of an atom. Atomic radii follow two trends - the radius decreases from left to right within a period and increases from top to bottom within a group, as atoms gain electron shells further from the nucleus with increasing atomic number.

3. The distance b/w the
nucleus the outermost
shell of an atom is called
atomic size or radius.

4. Atomic Radii follows two
trends:
 PERIODS:
 GROUPS:

5. In periods the atomic
radius decreases from
left to right.
DECREASES

6. In groups atomic radius increases
from top to bottom.
decreases
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