No

Nobelium

Identification

CAS Number: 10028-14-5

Discovery Year: 1957

Discoverer: Nobel Institute for Physics

Discovery Location: Sweden

Properties

Atomic Mass: 259 →Density: 9.9 g/cm³ →

Atomic Dimensions

Van der Waals Radius: 246 pm

Thermodynamics

Melting Point: 1100 K →

Electronic Structure

Electron Config: [Rn] 5f14 7s2

Block: f

Period: 7 →

Oxidation States: +2, +3

Abundance & Geochemistry

Goldschmidt Class: synthetic

About

Radioactive metallic transuranic element, belongs to the actinoids. Seven known isotopes exist, the most stable being No-254 with a half-life of 255 seconds. First identified with certainty by Albert Ghiorso and Glenn T. Seaborg in 1966. Unnilbium has been proposed as an alternative name.

Isotopes

No-255 255 ☢ 3.52 min

No-259 259 ☢ 58.0 min