State the factors which affect the atomic size of elements in a periodic table. In period 2 from left to right, state which element has the largest atomic size and which has the smallest, giving reasons.

Factors affecting atomic size:

1. Number of shells: More shells increase atomic size as the distance between the outermost shell and nucleus increases.
2. Nuclear charge: Higher nuclear charge decreases atomic size as electrons are attracted more strongly to the nucleus.

In Period 2, Li has the largest atomic size and F has the smallest. This is because nuclear charge increases from left to right, pulling the outermost shell closer to the nucleus.