Lawrencium (Lr)

Lawrencium properties

Atomic number

103

Atomic mass

266 u

Category

Actinide

Group

—

Period

7

Block

f-block

State at room temp.

Solid

Electronegativity

1.3

Melting point

1,900 K (1,626.8 °C)

Boiling point

—

Density

—

Valence electrons

3

Common charges

+3

Oxidation states

+3

Atomic radius

—

Ionization energy

—

Electron affinity

—

Radioactive

Yes, no stable isotopes

Discovered

1961

Lawrencium electron configuration

The electron configuration of Lawrencium (Lr) is [Rn] 5f14 7s2 7p1. Its 103 electrons are arranged in shells as 2, 8, 18, 32, 32, 8, 3.

Protons, neutrons and electrons in Lawrencium

A neutral Lawrencium atom has 103 protons and 103 electrons. Most Lawrencium atoms have about 163 neutrons: the atomic mass rounded to 266, minus the atomic number 103.

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

How many valence electrons does Lawrencium have?

3

Lawrencium has 3 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

Lawrencium 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 Lawrencium

266 g/mol

One mole of Lawrencium atoms (6.022 × 10²³ atoms) has a mass of 266 grams. Use this value to convert between grams and moles.

Lawrencium facts

• Lawrencium's symbol was originally Lw, but it was changed to Lr in 1963.
• Its longest-lived known isotope, lawrencium-266, has a half-life of about 11 hours.
• Lawrencium (Lr) has atomic number 103 and is a solid at room temperature. It was discovered in 1961.

Position in the periodic table

Lawrencium is element 103, 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 Lawrencium

Lawrencium has no uses outside research, since it is made only a few atoms at a time in particle accelerators. Scientists study it to learn how relativistic effects change the arrangement of its electrons. In 2015 an experiment at the Japan Atomic Energy Agency measured its first ionization energy, which turned out to be unusually low, as theory predicted.

Who discovered Lawrencium?

Albert Ghiorso, Torbjørn Sikkeland, Almon Larsh and Robert Latimer first reported lawrencium in 1961 at Berkeley by bombarding californium with boron ions, and work at Dubna in the following years helped confirm it. It was named after Ernest Lawrence, inventor of the cyclotron.

Where does the name come from?

Lawrencium honors Ernest O. Lawrence, the American physicist who invented the cyclotron, a type of particle accelerator. It was first made in 1961 at the Berkeley laboratory he founded, which now bears his name.

Discovery timeline