Periodic table group
Group 17
Group 17 is a vertical column of the periodic table containing Fluorine, Chlorine, Bromine, Iodine, Astatine, Tennessine. Elements in the same group have the same number of valence electrons, which is why they show related chemical behavior. The halogens. One electron short of a full shell, they form -1 halide ions and diatomic molecules, with reactivity falling from fluorine down the group.
At a glance
- Elements
- 6
- Atomic numbers
- 9 to 117
- Block
- p-block
- Periods
- 2, 3, 4, 5, 6, 7
- Phase at STP
- gas (2), liquid (1), solid (1)
Shared properties
- Same valence electron count, so members react in related ways
- Atomic radius increases down the group as electron shells are added
- First ionization energy generally decreases down the group
The 6 elements
Frequently asked questions
What elements are in group 17?
Group 17 contains 6 elements: Fluorine, Chlorine, Bromine, Iodine, Astatine, Tennessine.
What properties do group 17 elements share?
Elements in group 17 have the same number of valence electrons, so they react in related ways. Atomic radius increases down the group as electron shells are added, and first ionization energy generally decreases down the group. The halogens. One electron short of a full shell, they form -1 halide ions and diatomic molecules, with reactivity falling from fluorine down the group.
Why are they called the halogens?
Group 17's elements are the halogens. One electron short of a full shell, they form -1 halide ions and diatomic molecules, with reactivity falling from fluorine down the group.