Unknown propertiesElement 117 · p-block

Tennessine (Ts)

Tennessine (Ts), element 117, is a synthetic superheavy element whose chemical properties have not been measured; its most stable known isotope has mass number 294. Only a few atoms have ever been made, so its bulk properties are predictions.

117TsTennessine[294]

Atomic number

117

protons

Atomic weight

[294]

most stable isotope

Melting point

—

Boiling point

—

Density

7.2 g/cm³

predicted

Electronegativity

—

Pauling scale

State at 25 °C

Unknown

predicted solid

Discovered

2010

Russia (Dubna)

Tennessine at a glance

Identity

Symbol	Ts
Atomic number (Z)	117
Atomic weight	[294] mass number of the most stable isotope
Category	Unknown properties
Group	17 — halogens
Period	7
Block	p-block
CAS number	87658-56-8

Atomic properties

Electron configuration	[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵ Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p⁵
Electrons per shell	2, 8, 18, 32, 32, 18, 7
Covalent radius	165 pm

Physical properties

State at 25 °C	Unknown (predicted solid)
Density	7.2 g/cm³ (predicted)

Isotopes & abundance

Natural occurrence	Synthetic
Radioactive	Yes
Most stable isotope	²⁹⁴Ts — half-life 70 ms
Known isotopes	4

Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.

Tennessine electron configuration

Tennessine has 117 electrons. Written in short form, its ground-state configuration is [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵ — the electrons of the noble gas radon, plus 5f¹⁴ 6d¹⁰ 7s² 7p⁵.Written out in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p⁵.

As a member of group 17 it has 7 valence electrons in its outer shell (shell 7), which largely decide its chemistry.

5f↑↓↑↓↑↓↑↓↑↓↑↓↑↓

6d↑↓↑↓↑↓↑↓↑↓

7s↑↓

7p↑↓↑↓↑

Discovery and name

Discovered

2010 — Joint Institute for Nuclear Research with Oak Ridge and Lawrence Livermore National Laboratories and Vanderbilt University · Russia (Dubna).

Name

Tennessee, home of Oak Ridge National Laboratory.

Known for

The second-heaviest known element, made using berkelium-249 produced at Oak Ridge.

Isotopes of tennessine

Tennessine has no stable isotopes and does not occur naturally in significant amounts. Its longest-lived known isotope is:

Isotope	Protons	Neutrons	Half-life
²⁹⁴Ts	117	177	70 ms

4 isotopes of tennessine are known in our data set (half-lives as published in nuclear data tables).

Tennessine compared with group 17

The other elements in group 17 (halogens), from top to bottom of the table:

Element	Z	Atomic weight	Melting point	Boiling point	Density	Electronegativity
Fluorine	9	18.998	-220 °C	-188 °C	1.696 g/L	3.98
Chlorine	17	35.45	-101 °C	-34 °C	3.2 g/L	3.16
Bromine	35	79.904	-7.2 °C	59 °C	3.103 g/cm³	2.96
Iodine	53	126.90	114 °C	184 °C	4.933 g/cm³	2.66
Astatine	85	[210]	302 °C (est.)	—	7 g/cm³ (pred.)	2.2
Tennessine	117	[294]	—	—	7.2 g/cm³ (pred.)	—

Frequently asked questions

4 answers

What is the atomic mass of tennessine?

Tennessine has no stable isotopes, so it has no standard atomic weight. Periodic tables show [294], the mass number of its most stable known isotope.

How many protons, neutrons and electrons does tennessine have?

A neutral tennessine atom has 117 protons and 117 electrons. Its most stable isotope, tennessine-294, has 177 neutrons.

What is the electron configuration of tennessine?

[Rn] 5f¹⁴ 6d¹⁰ 7s² 7p⁵ (in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 6d¹⁰ 7s² 7p⁵).

Who discovered tennessine?

2010 — Joint Institute for Nuclear Research with Oak Ridge and Lawrence Livermore National Laboratories and Vanderbilt University (Russia (Dubna)).