How does the nature of oxides vary in the third period?

How does the atomic size of elements vary in a period of the perioedic table ? Give reasons for your answer.

Does the nature of the oxides of elements in a period change from strongly basic to strongly acidic ?

How does the acidic or basic nature of oxides change in a period?

How does metallic character vary in the group and period?

How does the atomic radius vary in a period of elements?

What is valency of an element? How does it vary with respect to hydrogen in the third period.