What trend occurs as you go down Group 7 in the periodic table?

As you move down Group 7 of the periodic table, known as the halogens, there are several noticeable trends. One key trend is the increase in atomic size. This occurs because each successive element has an additional electron shell compared to the one above it. As a result, the outermost electrons are located further from the nucleus, which leads to a larger atomic radius.

This increase in atomic size impacts the properties of the halogens as a whole and is reflective of their position in the periodic table. The greater distance of the outer electrons from the nucleus also contributes to other trends, such as an increase in relative atomic masses and a decrease in reactivity, but the main focus here is the increase in atomic size.

In contrast, as you move down the group, melting and boiling points actually increase rather than decrease, and reactivity tends to decrease due to the difficulty of these larger atoms gaining an additional electron compared to their smaller counterparts. This is not aligned with the provided response choices. Thus, the trend of increased atomic size is the defining characteristic as you progress down Group 7.