Element category
Halogens
The halogens are the reactive nonmetals of group 17, from fluorine to astatine. Each atom is one electron short of a noble gas configuration, so the group forms -1 halide ions and diatomic molecules and reacts readily with metals to give salts. The family name means salt former.
At a glance
- Elements
- 5
- Atomic numbers
- 9 to 85
- Block
- p-block
- Periods
- 2, 3, 4, 5, 6
- Phase at STP
- gas (2), liquid (1), solid (1)
Shared properties
- Seven valence electrons, one short of a full shell, so they form -1 halide ions
- Exist as diatomic molecules in the elemental state
- Reactivity decreases down the group; fluorine is the most electronegative element
- React with metals to form salts such as sodium chloride