Question

Why are periods with heavier elements longer than periods with lighter elements?

Answer 1

Answer:

The trend in properties from the lighter to the heavier element may attributed to change in the strength of binding of the outer electron.

Explanation:

The properties of elements in the same group of the periodic system are, although similar, not identical. The trend in properties from the lighter to the heavier elements may be attributed to changes in the strength of binding of the outer electrons and especially to the increasing size of the atoms.