F, Cl, and Br are three elements with 7 valence electrons. Among the three elements, which has the largest atomic radius and whihc one is the most reactive element, respectively?

• Bromine (Br) has the largest atomic radius as it has 4 shells, whereas F and Cl have 2 and 3 shells, respectively. The atomic size increases down the group due to an increase in shell number.
• Fluorine is the most reactive element as it has the smallest size and can gain electrons easily due to higher nuclear attraction on the incoming electron.

Hence, Br has the largest atomic radius and F is the most reactive among F, Cl, and Br.