---
title: "Nobelium (No) — element 102"
description: "Nobelium is element 102, symbol No, most stable isotope 259. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/nobelium/
site: "At One Place"
---

# Nobelium (No)

**Nobelium — element 102: No**

[259] · Actinide · period 7

Nobelium is the only actinide whose most stable oxidation state is +2 rather than +3, because its 5f subshell is full and prying an electron out of it costs more than the chemistry gains — a relativistic effect that makes nobelium behave a little like the alkaline earth metals. It also has the messiest discovery history in the table: a Stockholm claim in 1957 could not be reproduced, Berkeley and Dubna both claimed it afterwards, and IUPAC eventually awarded priority to Dubna while keeping the Swedish name.

## Properties

- **Atomic number:** 102
- **Symbol:** No
- **Mass number of most stable isotope:** [259]
- **Category:** Actinide
- **Period:** 7
- **Block:** f-block
- **Electron configuration:** [Rn] 7s² 5f¹⁴
- **Electrons per shell:** 2, 8, 18, 32, 32, 8, 2
- **Oxidation states:** +2, +3
- **Discovered:** 1966 by Georgy Flerov and colleagues at Dubna; earlier claims from Stockholm and Berkeley were not confirmed

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴
- **Noble gas shorthand:** [Rn] 7s² 5f¹⁴
- **Shells:** K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 8 · Q: 2

## What it is used for

- Research only; no application outside the laboratory

## Hazards

- Intensely radioactive; exists only as individual atoms in an accelerator

> Melting point, boiling point, density and electronegativity are omitted: no measured values exist. The mass given is the mass number of nobelium-259, the longest-lived at 58 minutes.

> Several physical properties are not listed for nobelium because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 100 | Fermium | Fm | [257] |
| 101 | Mendelevium | Md | [258] |
| 102 | Nobelium ← | No | [259] |
| 103 | Lawrencium | Lr | [266] |
| 104 | Rutherfordium | Rf | [267] |

## Common questions

### What is the atomic number of nobelium?

102. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for nobelium?

No.

### What is the electron configuration of nobelium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴, or [Rn] 7s² 5f¹⁴ in noble-gas shorthand.

## Related pages

- [Fermium (Fm)](https://atoneplace.net/element/fermium/)
- [Mendelevium (Md)](https://atoneplace.net/element/mendelevium/)
- [Lawrencium (Lr)](https://atoneplace.net/element/lawrencium/)
- [Rutherfordium (Rf)](https://atoneplace.net/element/rutherfordium/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)