Tennessine (Ts)

Tennessine was the last of the seventh period to be filled in, and making it required 22 milligrams of berkelium-249 grown over two years in Oak Ridge's reactor, flown to Russia, and bombarded before it decayed — the target had a shelf life of months. Six atoms were produced in the first campaign. It is filed as a halogen because it sits in group 17, but calculations suggest it would not behave like one: relativistic effects should make the −1 state unfavourable, so tennessine may be closer to a metal than to iodine.

Properties

Atomic number

117

Symbol

Ts

Mass number of most stable isotope

[294]

Category

Halogen

Group

17

Period

7

Block

p-block

Electron configuration

[Rn] 7s² 5f¹⁴ 6d¹⁰ 7p⁵

Electrons per shell

2, 8, 18, 32, 32, 18, 7

Oxidation states

+5, +3, +1, -1

Discovered

2010 by A Dubna, Oak Ridge, Livermore and Vanderbilt collaboration

Electron configuration

Full

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p⁵

Noble gas shorthand

[Rn] 7s² 5f¹⁴ 6d¹⁰ 7p⁵

Shells

K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 18 · Q: 7

What it is used for

• Research only; no application outside the laboratory

Hazards

• Intensely radioactive; exists only as individual atoms in an accelerator

Melting point, boiling point, density and electronegativity are omitted: no measurement is possible. Named for the state of Tennessee, the second US state to have an element named after it after California. The mass given is the mass number of tennessine-294, the longest-lived at roughly 50 milliseconds.

Several physical properties are not listed for tennessine because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

Neighbours in the table

Group 17

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Tennessine sits in group 17 with fluorine, chlorine, bromine, iodine, astatine.