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Element 85 · Astatine (At)

Astatine Bohr model: diagram and electrons per shell

The astatine Bohr model shows a astatine atom (At) as a small nucleus with its electrons circling it in 6 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P. This page has a rotating 3D astatine Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the astatine Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of astatine (At), a simplified picture of a single astatine atom. Its nucleus holds 85 protons, and a neutral astatine atom has 85 electrons, arranged around it in 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P).

At K · 21s2 L · 82s2 2p6 M · 183s2 3p6 3d10 N · 324s2 4p6 4d10 4f14 O · 185s2 5p6 5d10 P · 76s2 6p5

Astatine Bohr model diagram

Bohr model diagram of astatine: a nucleus of 85 protons with 85 electrons on 6 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P, each ring labelled with its shell letter.
The astatine Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P).

Astatine electrons per shell

A neutral astatine atom has 85 electrons, one for each of its 85 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P.

Electrons in each shell of the astatine Bohr model
ShellShell number (n)ElectronsMost it can hold (2n²)Subshells
K1221s2
L2882s2 2p6
M318183s2 3p6 3d10
N432324s2 4p6 4d10 4f14
O518505s2 5p6 5d10
P67726s2 6p5

How the astatine Bohr model builds up, shell by shell

Watch the astatine Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P) as it forms.

Animation of the astatine Bohr model being built: a nucleus of 85 protons appears first, then each shell grows in around it and takes its electrons, giving 85 electrons on 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P).
The astatine Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P. Protons are red, neutrons yellow and electrons blue.

How to draw the astatine Bohr model

  1. Find the atomic number. Astatine has atomic number 85, so a neutral atom has 85 protons and 85 electrons.
  2. Draw the nucleus. Put a circle in the centre and write At in it. The 85 protons sit there with the neutrons.
  3. Draw the shells. Sketch 6 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
  4. Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O and 7 in shell P.
  5. Check the total. 2 + 8 + 18 + 32 + 18 + 7 = 85, the atomic number, so every electron is accounted for.

Atomic data for the astatine Bohr model

The numbers behind the astatine Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol
At
Atomic number
85
Atomic mass
[210] u
Family
Halogens
Position
group 17, period 6
Block
p-block

Electron configuration

Full
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p5
Shorthand
[Xe] 4f14 5d10 6s2 6p5
Electrons per shell
2, 8, 18, 32, 18, 7
Outer-shell electrons
7 in shell P

Ionisation energies

I₁
899.003

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Calculated (pm)
127
Covalent (pm)
147
Van der Waals (pm)
202

Electronegativity and electron affinity

Electronegativity (Pauling)
2.2
Electron affinity (kJ/mol)
233

Oxidation states

−1 +1

Charges the element commonly takes in compounds.

Physical properties, abundance and history of astatine

Bulk properties of astatine, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions
Solid
Appearance
Unknown, probably metallic
Melting point
301.85°C (575 K)
Boiling point
336.85°C (610 K)
Density
6.35 g/cm³

Discovery

Discovered by
Dale R. Corson
Year
1940

Common compounds

  • Astatine-211 At
  • [2,2-bis(hydroxymethyl)-3-(2-nitroimidazol-1-yl)propyl](211At)astatine-211 C8H12AtN3O4
  • [3-[2-(2-nitroimidazol-1-yl)ethylcarbamoyl]phenyl](211At)astatine-211 C12H11AtN4O3
  • [4-[4-[3-[4-[[2-[(2S)-2-cyano-4,4-difluoropyrrolidin-1-yl]-2-oxoethyl]carbamoyl]quinolin-6-yl]oxypropyl]piperazine-1-carbonyl]phenyl](211At)astatine-211 C31H31AtF2N6O4
  • [4-[4-[4-[3-[4-[[2-[(2S)-2-cyano-4,4-difluoropyrrolidin-1-yl]-2-oxoethyl]carbamoyl]quinolin-6-yl]oxypropyl]piperazin-1-yl]-4-oxobutyl]phenyl](211At)astatine-211 C34H37AtF2N6O4
  • Hydrogen astatide AtH
  • 5-Astato-2'-deoxyuridine C9H11AtN2O5
  • 6-Astatomethyl-19-norcholest-5(10)-en-3-ol C27H45AtO

Compounds listed in the PubChem database.

Main isotopes of astatine

Isotopes of astatine share the same 85 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of astatine: mass number, abundance, half-life and decay
Mass numberNatural abundanceHalf-lifeDecay
206–30.6 minβ⁺, α
207–1.81 hβ⁺, α
208–1.63 hβ⁺, α
209–5.42 hβ⁺, α
210–8.1 hβ⁺, α
211–7.214 hEC, α

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about astatine