Tennessine at a glance
- Atomic number
- 117
- Symbol
- Ts
- Atomic mass
- 294 u
- Category
- Halogen
- Group / period
- 17 / 7
- Electron configuration
- [Rn] 5f 14 6d 10 7s 2 7p 5
- State at 25 °C
- Unknown
- Melting point
- n/a
- Boiling point
- n/a
- Density
- 7.2 g/cm³
- Electronegativity
- n/a
- 1st ionization energy
- 742 kJ/mol
- Oxidation states
- n/a
- Discovered
- 2010
Atomic structure
A neutral tennessine atom has 117 protons and 117 electrons, and its most common isotope carries about 177 neutrons. One atom weighs about 4.88 × 10⁻²⁵ kg, so a mole of tennessine (6.022 × 10²³ atoms) weighs 294 g. That nucleus holds 1.51 neutrons for every proton, typical of heavy nuclei, which need extra neutrons to hold together against the protons' repulsion. The electrons fill 7 shells (K 2, L 8, M 18, N 32, O 32, P 18, Q 7), which gives the configuration [Rn] 5f 14 6d 10 7s 2 7p 5. With 7 electrons in its outer shell, it tends to gain or share electrons to complete its outer shell. Every isotope is radioactive and short-lived; only a handful of atoms have ever been made, one at a time.
Physical properties
So little tennessine has ever existed at once that its melting point, boiling point and even its state at room temperature are unknown. Its density is 7.2 g/cm³ (predicted), 7.2 times as dense as water.
Chemical behaviour
It has no measured electronegativity. Pulling off its outermost electron takes 742 kJ/mol (predicted), less than Astatine above it (899 kJ/mol). Group 17 also holds Fluorine, Chlorine, Bromine, Iodine and Astatine, which share its outer-shell pattern. Its Lewis symbol is Ts surrounded by 7 dots. Handle with care: as a pure element it is radioactive.
Where it comes from
It does not occur in nature in useful amounts; it is made in nuclear reactors or particle accelerators. It was first made at Dubna, with Oak Ridge and Vanderbilt in Tennessee, which supplied the berkelium target by fusing berkelium-249 with calcium-48. Its longest-lived known isotope is Ts-294, about 50 milliseconds. It was first identified in 2010, making it the 118th element to be discovered (counting the 11 known since antiquity together).