Element 102
Nobelium (No)
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
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| No-259 | 259.10103 | - | 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.