Einsteinium is a synthetic element with the symbol Es and atomic number 99. It is the heaviest member of the actinide series, and is the ninth transuranium element. Einsteinium is a solid at room temperature, and is a silvery-white metal. It is radioactive, with a half-life of 276 days. Einsteinium is also pyrophoric, meaning that it can ignite spontaneously in air.

Some of the physical properties of einsteinium are:

* Atomic number: 99

* Atomic weight: 252.053

* Melting point: 860 °C

* Boiling point: 1,260 °C

* Density: 8.84 g/cm³

* Crystal structure: Face-centered cubic

* Color: Silvery-white

* Radioactive: Yes, with a half-life of 276 days

* Pyrophoric: Yes, can ignite spontaneously in air

Einsteinium is a very rare element, and only a few grams of it have ever been produced. It is used in scientific research, and has no commercial applications.