Bk Berkelium

Quick answerBerkelium (Bk) is an actinide with atomic number 97 and a mass number of 247 (the most stable isotope), in period 7. It was discovered by Thompson, Ghiorso, and Seaborg in 1949. It is used for synthesising heavier elements and actinide research. Its electron configuration is [Rn] 5f9 7s2.

Berkelium is a synthetic actinide made in tiny amounts, used only to create heavier elements and study actinide chemistry.

Key facts

Symbol	Bk
Atomic number	97
Atomic mass	[247] — mass number of the most stable isotope
Category	actinide
Group	— (f-block element, no group number)
Period	7
Block	f-block
Electron configuration	[Rn] 5f9 7s2
Discovered	Thompson, Ghiorso, and Seaborg, 1949
Uses	synthesising heavier elements, actinide research, target material

Quick quiz

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

1. What is the chemical symbol of Berkelium?

Ac Pa Bk Th

2. What is the atomic number of Berkelium?

99 98 97 96

3. Which category does Berkelium belong to?

alkali metal halogen actinide noble gas

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Keep exploring

• Periodic table — all 118 elements
• Uranium (U) — another actinide, atomic number 92
• 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
• 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
• Nobelium (No) — another actinide, atomic number 102
• All actinide elements — on the periodic table

Sources & last updated

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

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