About

Hassium is named after the German state of Hesse, where it was first synthesized at the GSI Helmholtz Centre for Heavy Ion Research. It is a synthetic, radioactive element with chemical properties predicted to be similar to osmium, its lighter homologue in group 8. Its most stable known isotope has a half-life of about 10 seconds, making detailed study exceptionally challenging.

Atomic Properties

Atomic Number108

Atomic Weight277 u

Neutrons (common)169

Electron Configuration[Rn] 5f¹⁴ 6d⁶ 7s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d⁶ 7s²

Electrons per Shell2, 8, 18, 32, 32, 14, 2

Oxidation States+8, +6, +4, +2

Periodic Table Position

Group8

Period7

BlockD

Chemical SeriesTransition metals

Physical Properties

State at STPsolid

Appearancepredicted to be a silvery metal

Crystal Structurehcp

Magnetic Orderingparamagnetic

Discovery

Discovered byGesellschaft für Schwerionenforschung

Discovery Year1,984

Occurrencesynthetic

CAS Number54037-57-9

Electron Configuration

Energy

↿⇂

1s

↿⇂

2s

↿⇂

2p

↿⇂

3s

↿⇂

3p

↿⇂

4s

↿⇂

3d

↿⇂

4p

↿⇂

5s

↿⇂

4d

↿⇂

5p

↿⇂

6s

↿⇂

4f

↿⇂

5d

↿⇂

6p

↿⇂

7s

↿⇂

5f

↿⇂

↿

6d

7p

Isotopes of Hassium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²⁷⁷Hs	277.151990	—	12 ms	Spontaneous Fission, Alpha Decay