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Astatine (At) – Element 85 of the periodic table

Astatine (symbol At) is element number 85 of the periodic table and belongs to the “Halogen” category. Its atomic mass is about 210, and its phase under standard conditions is Solid. This element sits in period 6 and group 17 of the periodic table, and its electrons are arranged in shells of 2, 8, 18, 32, 18, 7. The short electron configuration of Astatine is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵. Known uses of Astatine include Radiation therapy and Scientific research.

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Properties of Astatine

Atomic number
85
Chemical symbol
At
Atomic mass
210
Category
Halogen
Period
6
Group
17
Phase
Solid
Protons
85
Electrons
85
Neutrons (approx.)
125
Electron shells
2, 8, 18, 32, 18, 7
Outer-shell electrons
7
Discovered
Dale R. Corson (1940)

Electron configuration of Astatine

The electron configuration of Astatine (At), with 85 electrons, is shown below. The last shell (shell 6) is highlighted:

Full configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁵
Short configuration
[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵
Last shell
6s² 6p⁵

What is electron configuration and how is it written?

Electron shells of Astatine

Distribution of 85 electrons of Astatine across shells K to P:

  1. K2
  2. L8
  3. M18
  4. N32
  5. O18
  6. P7

What is a halogen?

The halogens are the group 17 elements: highly reactive nonmetals that form salt compounds with metals.

Uses of Astatine

Frequently asked questions about Astatine

What is the atomic number of Astatine?

The atomic number of Astatine (At) is 85; that is, every atom of it has 85 protons.

What is the electron configuration of Astatine?

The electron configuration of Astatine (At) is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁵; in short form it is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵, and its last shell is 6s² 6p⁵.

What is the chemical symbol of Astatine?

The chemical symbol of Astatine is At.

Where is Astatine located in the periodic table?

Astatine is located in period 6 and group 17 and belongs to the “Halogen” category.

What is the atomic mass of Astatine?

The atomic mass of Astatine is about 210 (atomic mass units).

What is the phase of Astatine under normal conditions?

The phase of Astatine under standard conditions is Solid.

What are the uses of Astatine?

Uses of Astatine include Radiation therapy and Scientific research.

Who discovered Astatine?

Astatine was discovered by Dale R. Corson in 1940.

Elements in the same category as Astatine (Halogen)

Fluorine (F)Chlorine (Cl)Bromine (Br)Iodine (I)Tennessine (Ts)

See all Halogens

Astatine’s group 17 neighbours

Fluorine (F)Chlorine (Cl)Bromine (Br)Iodine (I)Tennessine (Ts)

Group 17 of the periodic table