Question

Write the number of periods in the modern periodic table state the change in valency and metallic character of elements as we move from left to right across a period also state the change if any in the valency and atomic size of element as we move down a group.​

Answer 1

Answer:

Explanation:

There are 7 periods in the modern periodic table. Metallic character tends to decrease going across a period whereas the number of valence electrons increases in a period. Atomic radius increases from top to bottom within a group. This is caused by electron shielding. In a group, the number of the valence electron does not change. Hence, all the elements of one group have the same valency.