Question

12) Indicated whether the statements below are true or false by circling the correct option. If the statement is false, rewrite it so that it becomes true. (15 points) a) lonization energy increases from, left to right across a period because effective nuclear charge increases.a duus ncuons hardur to mate e True False b) Electron affinity for elements in group 17 becomes more favorable when moving from fluorine down to iodine. True False c) For the following isoelectronic series, ionic radius follows the order Li<Be2<B3C True False d) The lower than expected ionization energy of Al compared with Mg can be attributed to a change in the angular momentum quantum number for the third valence electron in Al. True False e) Moving from antimony (Sb) up to nitrogen (N), atomic radius increases True False

Answer 1

a) True

Ionization energy of an element is defined as the amount of energy required to remove the most loosely bound electron from an atom of the element in the gas phase. Within each period, from left to right atomic size decreases and nuclear charge increases. Thus ionization energy increases from left to right within the period.

b) True

Electron affinity of an element is defined as the amount of energy released when an electron is added to neutral gaseous atom. Generally electron affinity decreases from top to bottom within the group. This is because moving from top to bottom in a group atomic size increases.

In group 17 also trend is same. But there is one exception. Fluorine has low value of electron affinity compared to that of chlorine. This is due to the strong interelectronic repulsions in the relatively small and compact6 2p subshell on the addition of another electron.

c) False

For the following isoelectronic series, ionic follows the order C⁴⁺ < B³⁺ <Li⁺ <Be²⁺

d) True

Angular quantum number determines the shape of the orbital. That means s, p, d. f etc. The last valence electron of Al enters into 3p orbital (subshell). In Mg the valence electron enters into 3s orbital. Thus the change in atomic radius increases from Mg to Al. Thus ionization energy decreases.

e) False

Moving from antimony to nitrogen atomic size decreases.