Einsteinium

Symbol: Es
Atomic number: 99
Category: actinides
Group: n/a
Period: 7
Block: f
Atomic weight: (252) g/mol
Electrons per shell: 2, 8, 18, 32, 29, 8, 2
CAS number: 7429-92-7
Phase: solid
Density: 8.84 kg/l (near room temperature)
Melting point: 1133 K (860C, 1580F)
Boiling point: unknown
Crystal structure: unknown
Oxidation states: 2, 3, 4
Electronegativity: 1.3 (Pauling scale)
Name's origin: Albert Einstein
Name's meaning: in honor of the theoretical physicist
Facts:
- is a metallic synthetic element
- its chemical and physical properties are similar to other metals
- though only small amounts have ever been made, it has been determined to be silver-colored
- like all synthetic elements, isotopes of einsteinium are extremely radioactive, and are considered highly toxic
- does not occur naturally in any measurable quantities
- the modern process of creating the element starts with the irradiation of plutonium-239 in a nuclear reactor for several years
- has no known uses, other than radioactivity
- nineteen radioisotopes of einsteinium have been characterized, with the most stable being einsteinium-252 with a half-life of 471.7 days