CBSE Class 11-science Answered

The attraction that a bonding pair of electrons for a particular nucleus depends on following facts:

• the number of protons in the nucleus;
• the distance from the nucleus;
• the amount of screening by inner electrons.

Electronegativity trend across group: The positively charged protons in the nucleus attract the negatively charged electrons. As the number of protons in the nucleus increases, the electronegativity or attraction will increase. Therefore electronegativity increases from left to right in a row in the periodic table.

Electronegativity trend across period: The electronegativity increases from bottom to top because the bonding pair of electrons is increasingly distant from the attraction of the nucleus.