102[259]NoNobelium
Nobelium (No) — element 102actinide · period 7
Nobelium is a chemical element with the symbol No and atomic number 102. It is an actinide in period 7 of the periodic table (the f-block), with a standard atomic mass of [259] u. At room temperature (25 °C) nobelium is predicted to be a solid.
💡 Known for: Named after Alfred Nobel; only small numbers of atoms have ever been made.
# Nobelium properties
| Symbol | No |
|---|---|
| Atomic number | 102 |
| Atomic mass | [259] u |
| Category | actinide |
| Group | — (f-block, no group number) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f¹⁴ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 7s² |
| Electrons per shell | 2, 8, 18, 32, 32, 8, 2 |
| Protons / electrons | 102 / 102 |
| State at 25 °C | predicted solid |
| Melting point | 1100 K (826.9 °C, 1520.3 °F) (predicted) |
| Boiling point | unknown |
| Density | — |
| Electronegativity (Pauling) | 1.3 |
| First ionization energy | 6.65 eV |
| Atomic radius | — |
| Discovered | 1958 |
Values for superheavy elements are theoretical predictions; none have been measured in bulk.
# Electron configuration of nobelium
The electron configuration of nobelium is [Rn] 5f¹⁴ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 7s². Its 102 electrons fill 7 shells as 2, 8, 18, 32, 32, 8, 2, so the outermost shell holds 2 electrons. Because only a few atoms have ever been made, this configuration is a theoretical prediction.
# Related elements
MdMendeleviumprevious elementLrLawrenciumnext elementAcActiniumactinideThThoriumactinidePaProtactiniumactinideUUraniumactinideNpNeptuniumactinidePuPlutoniumactinideAmAmericiumactinideCmCuriumactinide
# Nobelium FAQ
What is the atomic number of nobelium?
The atomic number of nobelium is 102: every nobelium atom has 102 protons in its nucleus. Its symbol is No.
What is the atomic mass of nobelium?
The standard atomic mass of nobelium is [259] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of nobelium?
Nobelium's electron configuration is [Rn] 5f¹⁴ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹⁴ 6s² 6p⁶ 7s²), with 2, 8, 18, 32, 32, 8, 2 electrons per shell.
Is nobelium a metal?
Yes. Nobelium is an actinide, one of the metals.
What is the melting point of nobelium?
Nobelium melts at 1100 K (826.9 °C, 1520.3 °F). These values are predictions.
What is nobelium used for / known for?
Named after Alfred Nobel; only small numbers of atoms have ever been made.