The periodic trend for electronegativity is similar to what other trend? a. the trend for shielding. b. the trend for ionic radii c. the trend for atomic radii d. the trend for first ionization energy

Option D: The trend for first ionization energy.

Electronegativity is defined as tendency of an atom of element to attract electron pair towards itself. On moving left to right in a period, electronegativity increases  due to increase in nuclear charge and on moving top to bottom in a group, it decreases due to increase of distance between nucleus and outermost shell.

Shielding decreases with increase in electronegativity. If the nuclear charge gets shielded by inner electrons, outer electrons will experience less nuclear charge and the tendency of an atom to attract electron/s decreases or electronegativity decreases. Thus, electronegativity trends can not be similar to the trends of shielding. Option A is wrong.

Ionic radius is defined as distance between the nucleus and outermost shell of an ion (charged atom) and atomic radius is distance between the nucleus and outermost shell of an atom. On moving left to right in a period, atomic and ionic radius decreases because  nuclear charge increases and it pulls the outer electrons more towards itself resulting decrease in size. Similarly, on moving top to bottom in a group, atomic and ionic radius increases due to addition of an extra period. Therefore, option B and C are wrong.

Ionization energy is the amount of energy needed to remove an electron from outer most shell of an atom. On moving left to right in a period, it increases due to increase in  nuclear charge, as outer electrons are more attracted to the nucleus. On moving top to bottom, due to increase in size, ionization energy decrease because small amount of energy is required to remove the outer shell electron/s. Therefore, trends for first ionization energy are similar to electronegativity trends and option D is correct.

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