Question

multiple - choice question
why does electronegativity decrease as you move down toward the bottom of the periodic table?
because atomic radius decreases
increasing protons decreases the attraction to the outermost electron
increasing shells lower the attraction of the outermost electron to the nucleus
because ionization energy increases

Explanation:

Electronegativity is the ability of an atom to attract electrons. As we move down a group in the periodic table, the number of electron shells increases. The outermost electrons are further from the nucleus, and the shielding effect (due to inner - shell electrons) reduces the effective nuclear charge experienced by the outermost electrons. This lower attraction of the outermost electron to the nucleus (because of increasing shells) leads to a decrease in electronegativity.

• Option 1: Atomic radius actually increases as we move down a group (more electron shells), so this option is incorrect.
• Option 2: Increasing protons would increase the positive charge of the nucleus. If there were no shielding effect, this would increase the attraction to the outermost electron. But the main factor is the increasing number of shells (shielding), not just the protons. So this option is incorrect.
• Option 3: As explained above, increasing shells (more electron - shell layers) lead to a lower attraction of the outermost electron to the nucleus, which is the reason for the decrease in electronegativity. This option is correct.
• Option 4: Ionization energy generally decreases as we move down a group (because it is easier to remove the outermost electron due to increased distance from the nucleus and shielding). So this option is incorrect.

Answer:

increasing shells lower the attraction of the outermost electron to the nucleus