Final answer:
The trend in electron affinities from aluminum to chlorine generally increases. This is because elements across a period tend to attract additional electrons more strongly with a higher nuclear charge. b is correct
Step-by-step explanation:
The trend in electron affinities from aluminum to chlorine is that electron affinities increase as you move across the period from left to right. This means that, in general, elements become more inclined to gain an electron and release energy in the process. However, it is important to acknowledge that the periodic trend can have exceptions due to variations in atomic structure and other factors.
When progressing from aluminum to chlorine in the periodic table, each element has a higher nuclear charge, thereby attracting additional electrons more strongly. This increasing tendency to attract an additional electron is reflected in the increasing (or more negative) electron affinity values. Additionally, as electrons are added from aluminum to chlorine, they fill orbitals that are in the same energy level but closer to the nucleus, which also contributes to the trend of increasing electron affinities.
Therefore, the correct option that describes the trend in electron affinities from aluminum to chlorine is: b) Increases. This is based on the general periodic trend which shows that electronegativity and electron affinity increase from left to right across a period.