Question

Write the number of periods the Modern Periodic Table has. State the changes in valency and metallic character of elements as we move from left to right in a period. Also state the changes, if any, in the valency and atomic size of elements as we move down a group.

Answer 1

The Modern Periodic Table has 7 periods. Valency across a period increases from 1 to 4, then decreases from 4 to zero.
Metallic character of elements across a period decreases.
Valency down a group remains the same. Atomic size of elements down a group increases.