Uranium (U)

Uranium properties

Atomic number

92

Atomic mass

238.03 u

Category

Actinide

Group

—

Period

7

Block

f-block

State at room temp.

Solid

Electronegativity

1.38

Melting point

1,405.3 K (1,132.2 °C)

Boiling point

4,404 K (4,130.8 °C)

Density

19.1 g/cm³

Valence electrons

2

Common charges

+3, +4, +5, +6

Oxidation states

+6, +5, +4, +3

Atomic radius

240 pm

Ionization energy

6.194 eV

Electron affinity

—

Radioactive

Yes, no stable isotopes

Discovered

1789

Uranium electron configuration

The electron configuration of Uranium (U) is [Rn] 5f3 6d1 7s2. Its 92 electrons are arranged in shells as 2, 8, 18, 32, 21, 9, 2.

Protons, neutrons and electrons in Uranium

A neutral Uranium atom has 92 protons and 92 electrons. Most Uranium atoms have about 146 neutrons: the atomic mass rounded to 238, minus the atomic number 92.

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

How many valence electrons does Uranium have?

2

Uranium 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

Uranium 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 Uranium

238.03 g/mol

One mole of Uranium atoms (6.022 × 10²³ atoms) has a mass of 238.03 grams. Use this value to convert between grams and moles.

Uranium facts

• Uranium was named after the planet Uranus, discovered just eight years earlier.
• Uranium (U) has atomic number 92 and is a solid at room temperature. It was discovered in 1789.

Position in the periodic table

Uranium is element 92, 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 Uranium

Uranium is the main fuel for nuclear power plants, where uranium-235 atoms split in a chain reaction that releases heat to make steam and electricity. Natural uranium is usually enriched to raise its uranium-235 content from about 0.7% to a few percent. Depleted uranium, which is very dense, is used in armor-piercing shells, radiation shielding and aircraft counterweights.

Who discovered Uranium?

German chemist Martin Heinrich Klaproth discovered uranium in Berlin in 1789 while analyzing the mineral pitchblende, although what he isolated was actually an oxide. French chemist Eugène-Melchior Péligot first isolated the metal itself in 1841.

Where does the name come from?

Uranium is named after the planet Uranus, discovered by William Herschel in 1781. Martin Heinrich Klaproth named the element in 1789; the planet itself honors Uranus, the Greek god of the sky.

Discovery timeline