Question

While going from top to bottom in group and left to right in period of a modern perodic table what changes will occur in following characterstics? They increase or decrease?

(i) Ionisation potential.
(ii) Valency
( iii) Atomic size
(iv) Electronegativity .​

Answer 1

Answer:

2) VALENCY

3) ATOMIC SIZE

4) ELECTRONEGATIVITY

Explanation:

1) On moving from left to right in a period, the chemical reactivity of elements first decreases and then increases. On moving from left to right in a period, the number of valence electrons increases from 1 to 8. On moving from left to right in a period, the atomic size decreases; the size of the atoms decreases. Since the atomic size decrease when we move from left to right in a period, therefore, electronegativity increases in moving left to right. Atomic size increases when moving down in a group thus electronegativity decreases when we move from top to bottom in the periodic table.

2) If we move from top to bottom in a group, the number of valence electrons remains the same. While moving across a period, the valence electrons increases. Valency is the combining capacity of elements or the number of electrons donated, accepted or shared during compound formation by the elements.

Answer 2

(i)While going top to bottom in a group ionisation potential will increase as the number of shells will increase.

In the period the ionisation potential will decrease as the size gets smaller.

(ii)In a group the valency remains the same as the general electronic configuration is same in a group.

For a period the valency first increases then decreases.

(iii)In a group the atomic size increases because the number of shells keeps increasing.

In a period the size decrease because the effective nuclear charge increases.

(iv)In a group the electronegativity decreases.As the number of shells increases, so the tendency to atract electron decreases.

In a period as the effective nuclear charge increases the electronegativity also increases.