Question

All the thing about the periodic table (modern) and about valency and atoms

Answer 1

Answer:

There are 7 periods in the modern periodic table. 

Metallic character tends to decrease on going across a period whereas the number of valence electrons increases in a period and valency first increases from 1 to 4 and then decreases from 4 to 0. 

Atomic radius increases from top to bottom within a group. This is caused by the addition of a new shell. In a group, the number of valence electrons does not change. Hence, all the elements of one group have the same valency.

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