For 10 points, name this group of elements which includes astatine, bromine, iodine, chlorine, and fluorine.
Members of this group of elements act as electrophiles when interacting with a Lewis base in its namesake bonding. Antoine-Jerome Ballard is often credited with extracting one of its members from seaweed, and magnesium reacts with one element in this group to form a Grignard reagent. Another member of this group is used to detect starch in a process named for Lugol. It is the only group to have solid, liquid, and gaseous elements at standard temperature and pressure, and four members of this group are diatomic. For 10 points, name this group of elements which includes astatine, bromine, iodine, chlorine, and fluorine.
Members of this group of elements act as electrophiles when interacting with a Lewis base in its namesake bonding.
Halogens [accept Group 17 or Group VIIA]