Element 85
Astatine
Halogens
Astatine (At) is in the p-block of the periodic table — group 17, period 6.
Astatine is a very rare radioactive chemical element with the chemical symbol At and atomic number 85.
Key data
- Atomic number
- 85
- Atomic mass
- 210.000 u
- Group / Period
- 17 / 6
- Block
- p-block
- Phase at STP
- Solid
- Density
- 6.35 g/cm³
- Melting point
- 301.9 °C
- Boiling point
- 336.9 °C
- Electron configuration
- [Xe] 4f14 5d10 6s2 6p5
Periodic table block
Astatine is in the p-block (group 17, period 6). Elements land in the p-block when their highest-energy electrons fill a p subshell — this region holds most nonmetals, the metalloids, and the metals on the right of the table.
New to this? Periodic table blocks explained: s, p, d, and f
Common uses
- •Cancer therapy research
- •Rarest natural element
- •Very short half-life
Discovery
Year: 1940
Discovered by: Dale R. Corson
Frequently asked questions
What is the atomic number of Astatine?
Astatine has atomic number 85. Its symbol is At and its atomic mass is 210 u.
What category of element is Astatine?
Astatine is classified as halogens. It sits in group 17, period 6 of the periodic table.
What block of the periodic table is Astatine in?
Astatine is in the p-block (group 17, period 6). Its highest-energy electrons occupy the p subshell — you can see this in its electron configuration, [Xe] 4f14 5d10 6s2 6p5.
What is Astatine used for?
Common uses of Astatine include: Cancer therapy research, Rarest natural element, Very short half-life.
When was Astatine discovered?
Astatine was discovered in 1940 by Dale R. Corson.
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