Element 102

Nobelium (No)

Actinide · Period 7 · f-block

Nobelium (No) is element 102 of the periodic table, an actinide in period 7 (f-block) with an atomic mass of 259 and is a solid at standard conditions.

At a glance

Atomic number
102
Symbol
No
Atomic mass
259 u
Category
Actinides
Period
7
Block
f-block
Phase at STP
solid

Electron structure

Electron configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f14 7s2
Shorthand configuration
[Rn] 5f14 7s2
Electrons per shell
2, 8, 18, 32, 32, 8, 2
Oxidation states
+2, +3

Physical properties

Nobelium has only ever been produced in quantities too small to weigh or observe in bulk. The physical and atomic values below are theoretical predictions from periodic trends and relativistic calculations, not measurements.

Melting point
1,100 K (826.85 °C) (predicted)
Density
9.9 g/cm³ (predicted)
Phase
solid

Atomic properties

Electronegativity (Pauling)
1.3 (predicted)
First ionization energy
642 kJ/mol (predicted)
Electron affinity
-223 kJ/mol (predicted)

Notable isotopes

Notable isotopes of Nobelium: mass number, atomic mass, natural abundance, and stability.
IsotopeMassAbundanceStability
No-259259.10103 - Half-life 58 minutes

Common uses

  • Scientific research only

Discovery

Year
1958
Discovered by
Albert Ghiorso, Glenn T. Seaborg
Country
USA

Frequently asked questions

Is nobelium a metal?
Yes. Nobelium is a metal, classified as an actinide on the periodic table.
How many protons does nobelium have?
Nobelium has 102 protons. Its atomic number is 102, which is also the number of electrons in a neutral atom of nobelium.
What group and period is nobelium in?
Nobelium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.
What is the atomic mass of nobelium?
The atomic mass of nobelium is 259 u (unified atomic mass units).

Keep exploring

Nobelium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.