Trends in Periodic Table

Question 1

What is atomic radii?

Answer 1

Atomic radii is half the distance between the nuclei of two atoms in a same element that were joined by single covalent bond.

Question 2

Why does atomic radii increases going down the group?

Answer 2

1. Electrons are going into new energy level which are further away from positive nucleus.
2. Screening effect of the inner electron act as wall between positive nucleus and outer electrons.

Question 3

How does screening effect increases the atomic radii?

Answer 3

Due to screening effect the attraction between positive nucleus and outer electron are weakened.Thus there will be more space in between nucleus and the outer electron.

Question 4

Why does atomic radii decreases along the period?

Answer 4

There is no extra screening effect as they are in the
energy levels.
Positive nuclear charge is increasing as the number of protons are increasing. Therefore the attraction between the positive nucleus and outer electron increases. As a result atomic radii decreases.

Question 5

What is electronegativity?

Answer 5

This is the relative attraction that an atom in a molecule has for a shared pair of electrons.

Question 6

Why does electronegativity increases across the period?

Answer 6

1. Increase in nuclear charge as the protons are increasing which results in greater attraction between nucleus and outer electrons.
2. Decrease in atomic radii due to increasing nuclear charge and no extra screening effect.