Which of the following atoms should have the highest 1st electron affinity ?FONC

The electron affinity of an atom is the amount of energy released when an electron is added to a neutral atom to form a negative ion.

In general, electron affinity increases from left to right across a period in the periodic table and decreases from top to bottom within a group. This is because as you move from left to right across a period, the number of protons in the nucleus increases, which increases the positive charge of the nucleus and the attraction for additional electrons.

In the case of the atoms listed in the question (F, O, N, C), they are all in the same period but in different groups. Therefore, we can use the rule that electron affinity increases from left to right across a period.

Looking at the periodic table, we can see that Fluorine (F) is furthest to the right of the four elements listed. Therefore, Fluorine should have the highest 1st electron affinity.