Recognised as Chemical element
Astatine
- At
- Z = 85
- halogen
- No stable isotope
Astatine (At) is element 85, a halogen in period 6 and group 17. Its most stable isotope has mass number 210. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolAt
Mass number of the most stable isotope210this element has no stable isotope
Mass in kilograms3.487132 × 10^-25
Categoryhalogen
Group17
Period6
Blockp-block
Electrons in a neutral atom85
Neutrons in the most common isotope125≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁵ground state, subshells written in order of n
Noble gas shorthand[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵
Electrons per shell2, 8, 18, 32, 18, 7K, L, M and outward
Electrons in the outer shell7
Unpaired electrons1Hund's rule; unpaired electrons make the free atom paramagnetic
Madelung ruleFollowedthe ground state is what the n + l filling order predicts
Quantities
Molar mass210 g/mol
Mass of one mole210 grams
Atoms in one gram2.8676861 × 10^21
Mass of one atom3.487132 × 10^-22 g
Keep nerding
Every link below is a page Nerdulator can generate from what it already knows about this value.
Neighbouring elements
The number
Nerdulate something else
Nothing in mind? Surprise me · today’s page