Berkelium (Bk)

Berkelium properties

Atomic number

97

Atomic mass

247 u

Category

Actinide

Group

—

Period

7

Block

f-block

State at room temp.

Solid

Electronegativity

1.3

Melting point

1,259 K (985.8 °C)

Boiling point

2,900 K (2,626.8 °C)

Density

14.78 g/cm³

Valence electrons

2

Common charges

+3, +4

Oxidation states

+4, +3

Atomic radius

244 pm

Ionization energy

6.23 eV

Electron affinity

—

Radioactive

Yes, no stable isotopes

Discovered

1949

Berkelium electron configuration

The electron configuration of Berkelium (Bk) is [Rn] 5f9 7s2. Its 97 electrons are arranged in shells as 2, 8, 18, 32, 27, 8, 2.

Protons, neutrons and electrons in Berkelium

A neutral Berkelium atom has 97 protons and 97 electrons. Most Berkelium atoms have about 150 neutrons: the atomic mass rounded to 247, minus the atomic number 97.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Berkelium have?

2

Berkelium has 2 valence electrons in its outermost shell. As an f-block element, its 4f or 5f electrons can also take part in bonding.

See every element: Periodic table with valence electrons

Berkelium orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Berkelium

247 g/mol

One mole of Berkelium atoms (6.022 × 10²³ atoms) has a mass of 247 grams. Use this value to convert between grams and moles.

Berkelium facts

• The first visible sample of a berkelium compound, made in 1962, weighed only about three billionths of a gram.
• Berkelium-249, the isotope most often used in research, has a half-life of about 330 days.
• Berkelium (Bk) has atomic number 97 and is a solid at room temperature. It was discovered in 1949.

Position in the periodic table

Berkelium is element 97, in period 7 of the periodic table. It is one of the Actinides in the f-block, shown in the rows below the main table.

All actinides

Uses of Berkelium

Berkelium has no uses outside scientific research because only tiny amounts have ever been made. Its main role is as a target for making heavier elements: about 22 milligrams of berkelium-249 produced at Oak Ridge National Laboratory were used to create tennessine in 2010. Chemists also study its compounds to learn how electrons behave in the heaviest elements.

Who discovered Berkelium?

Stanley Thompson, Albert Ghiorso and Glenn Seaborg first made berkelium in December 1949 at the University of California, Berkeley, by bombarding americium with alpha particles. It was named after the city of Berkeley, just as terbium, the element above it, is named after the Swedish village of Ytterby.

Where does the name come from?

Berkelium is named after the city of Berkeley, California, home of the University of California laboratory where it was first made in 1949. The name parallels terbium, the element above it, which is named after a Swedish village.

Discovery timeline