Hassium

Hassium is element 108 (Hs), located in period 7, group 8 and the d block. No macroscopic sample exists, so an ordinary room-temperature phase is not established experimentally. Its calculated electron configuration is [Rn] 5f14 6d6 7s2.

Atomic number108

Standard atomic weightNo standard atomic weight

Group8

Period7

Blockd

Electron configuration[Rn] 5f14 6d6 7s2

Electronic structure

What controls its chemistry

Hassium is a superheavy synthetic element. Only very small numbers of atoms have been produced, so its chemistry is studied through individual decay events and specialised atom-at-a-time experiments rather than bulk samples.

Its position in group 8 and the d block provides a first prediction of its chemistry, but relativistic effects become increasingly important for the heaviest nuclei. Experimental results are therefore essential before extending lighter-group trends too confidently.

Chemical forms

Compounds, ions and materials

Bulk hassium compounds cannot be prepared because only tiny numbers of short-lived atoms are produced. Chemical experiments, when possible, test adsorption, volatility or single-atom reactions and compare the results with lighter elements in the same group.

Physical behaviour

State and phase changes

No macroscopic sample has been produced, so ordinary bulk properties such as density, melting point and boiling point are not established experimentally. Published values for superheavy elements are generally theoretical predictions and should be labelled as such.

Occurrence and applications

Where hassium is found and used

In practice, hassium is encountered in scientific research.

In practice

Examples of real uses

Scientific research

Hassium is produced, isolated or measured mainly to test atomic, nuclear and periodic trends rather than for bulk commercial use.

Periodic position

What its neighbours tell us

Hassium is in period 7 and group 8. In the neighbourhood shown here, it lies between bohrium and meitnerium in the same period; osmium is directly above it in the same group. These positions make it possible to compare atomic size, ionisation energy and bonding behaviour with nearby elements.

Reference data

Physical and atomic properties

Classificationtransition metal

Phase at room temperatureNot established experimentally

Electron shells2 · 8 · 18 · 32 · 32 · 14 · 2

DensityNot established experimentally

Melting pointNot established experimentally

Boiling pointNot established experimentally

Pauling electronegativity—

First ionisation energy—

Electron affinity—

Values describe the element or neutral atom where applicable. Physical data can depend on allotrope, pressure and measurement conditions.

History

Discovery and identification

Hassium is synthetic. It is produced in nuclear-reaction experiments and identified from the decay chains of the atoms created. The quantities involved are far below anything that could form a visible sample.

Isotopes and atomic weight

How isotope composition changes the numbers

Hassium has no standard atomic weight. There is no characteristic terrestrial isotopic mixture from which a stable abundance-weighted average can be assigned.

Hassium has no stable isotope. Its isotopes are radioactive, and their half-lives and decay modes become important whenever the element is measured, handled or used.

Safety

Handling and exposure

Hassium is radioactive. Work with it requires radiological controls appropriate to the isotope, activity, radiation type and chemical form.