Question

Which of the following statements are not true.

• A. Down the group the electronegativity decreases.
• B. In a period, electronegativity decreases on moving from left to right.
• C. Electronegativity decreases with increase in size.
• D. Electronegativity decreases with the decrease in ionisation energy.

Answer 1

The correct option is B In a period, electronegativity decreases on moving from left to right.

Electronegativity is the ability of an atom to attract bonded electrons. The factors of electronegativity are

1) Size of the atom

2) Effective nuclear charge

The trend of electronegativity is as follows

In a period, the electronegativity increases as we go from left to right in the periodic table as the size of the atoms decreases and the nuclear charge increases. Therefore "In a period, electronegativity decreases on moving from left to right." is a wrong statement.

In a group, the electronegativity decreases as we go down the group as the size of the atom increases but the effective nuclear charge decreases. Therefore option "Down the group the electronegativity decreases." is the correct statement.

The ionisation energy is the energy required to remove a valence electron of an atom, the greater the nuclear charge the greater the ionisation energy and greater the electronegativity as well. Therefore if ionisation energy increases then electronegativity increases. Hence option "Electronegativity decreases with the decrease in ionisation energy." is the correct statement.

The greater the size the lesser the effective nuclear charge on the valence electrons and hence lesser the ability to attract bonded electrons. So, greater the size the lesser the electronegativity. Therefore the option " Electronegativity decreases with increase in size." is a correct statement.