No Nobelium

Quick answerNobelium (No) is an actinide with atomic number 102 and a mass number of 259 (the most stable isotope), in period 7. It was discovered by E. D. Donets and colleagues in 1965. It is used for actinide research and studying heavy-element chemistry. Its electron configuration is [Rn] 5f14 7s2.

Nobelium is a synthetic actinide whose very discovery was disputed for a decade between rival laboratories.

Key facts

Symbol	No
Atomic number	102
Atomic mass	[259] — mass number of the most stable isotope
Category	actinide
Group	— (f-block element, no group number)
Period	7
Block	f-block
Electron configuration	[Rn] 5f14 7s2
Discovered	E. D. Donets and colleagues, 1965
Uses	actinide research, studying heavy-element chemistry

Quick quiz

Three questions from the facts on this page. No sign-up, no score is saved.

1. What is the chemical symbol of Nobelium?

Th Ac Pa No

2. What is the atomic number of Nobelium?

102 101 103 104

3. Which category does Nobelium belong to?

halogen noble gas alkali metal actinide

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Keep exploring

• Periodic table — all 118 elements
• Neptunium (Np) — another actinide, atomic number 93
• Plutonium (Pu) — another actinide, atomic number 94
• Americium (Am) — another actinide, atomic number 95
• Curium (Cm) — another actinide, atomic number 96
• Berkelium (Bk) — another actinide, atomic number 97
• Californium (Cf) — another actinide, atomic number 98
• Einsteinium (Es) — another actinide, atomic number 99
• Fermium (Fm) — another actinide, atomic number 100
• Mendelevium (Md) — another actinide, atomic number 101
• Lawrencium (Lr) — another actinide, atomic number 103
• All actinide elements — on the periodic table

Sources & last updated

• CIAAW — Standard Atomic Weights
• PubChem Periodic Table
• Wikipedia — Timeline of chemical element discoveries
• Wikipedia — Nobelium

Last updated: 2026-11-12. Figures are shown with their year; where sources disagree, the value is left out rather than estimated.