Question

Compare the periodic trends of electronegativity and state the reasons for these variations.

a) Electronegativity increases across a period due to increasing effective nuclear charge.
b) Electronegativity increases down a group due to increased shielding and additional energy levels.
c) Electronegativity decreases across a period due to increased shielding.
d) Electronegativity decreases down a group due to increasing effective nuclear charge.

Answer 1

Electronegativity increases across a period due to increasing effective nuclear charge and decreases down a group due to increased shielding and additional energy levels.

Step-by-step explanation:

When comparing the periodic trends of electronegativity, it is observed that a) electronegativity increases across a period due to the increasing effective nuclear charge. This is because as you move from left to right, the number of protons in the nucleus increases, leading to a stronger attraction of electrons towards the nucleus, hence increasing electronegativity. Conversely, b) electronegativity decreases down a group which can be attributed to increased shielding and the addition of energy levels. This increased shielding by inner electrons prevents the outermost electrons from feeling the full effect of the nucleus, which makes the atom less able to attract bonding electrons and thus results in a decrease in electronegativity.

The other two options, c) and d), do not correctly describe the trends for electronegativity. Electronegativity does not increasedown a group nor does it decrease across a period. As such, these statements are not in line with the observed periodic trends for electronegativity.