Lutetium (Lu)

Lutetium properties

Atomic number

71

Atomic mass

174.97 u

Category

Lanthanide

Group

—

Period

6

Block

f-block

State at room temp.

Solid

Electronegativity

1.27

Melting point

1,925 K (1,651.8 °C)

Boiling point

3,675 K (3,401.8 °C)

Density

9.841 g/cm³

Valence electrons

2

Common charges

+3

Oxidation states

+3

Atomic radius

221 pm

Ionization energy

5.426 eV

Electron affinity

—

Radioactive

No, has stable isotopes

Discovered

1907

Lutetium electron configuration

The electron configuration of Lutetium (Lu) is [Xe] 4f14 5d1 6s2. Its 71 electrons are arranged in shells as 2, 8, 18, 32, 9, 2.

Protons, neutrons and electrons in Lutetium

A neutral Lutetium atom has 71 protons and 71 electrons. Most Lutetium atoms have about 104 neutrons: the atomic mass rounded to 175, minus the atomic number 71.

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

How many valence electrons does Lutetium have?

2

Lutetium 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

Lutetium 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 Lutetium

174.97 g/mol

One mole of Lutetium atoms (6.022 × 10²³ atoms) has a mass of 174.97 grams. Use this value to convert between grams and moles.

Lutetium facts

• Lutetium is the densest of the lanthanides and has the highest melting point in the series.
• It was the last of the stable rare earth elements to be discovered.
• Lutetium (Lu) has atomic number 71 and is a solid at room temperature. It was discovered in 1907.

Position in the periodic table

Lutetium is element 71, in period 6 of the periodic table. It is one of the Lanthanides in the f-block, shown in the rows below the main table.

All lanthanides

Uses of Lutetium

Lutetium is rare and costly, but it has important medical uses. Lutetium-177 is attached to molecules that seek out certain tumors, delivering radiation directly to prostate cancers and neuroendocrine tumors. Crystals containing lutetium are used as scintillators in PET scanners, flashing when hit by gamma rays. Geologists also use the slow decay of lutetium-176 to date ancient rocks and meteorites.

Who discovered Lutetium?

French chemist Georges Urbain discovered lutetium in Paris in 1907 by showing that ytterbium was a mixture of two elements; Carl Auer von Welsbach and Charles James separated it independently at about the same time. Urbain named it after Lutetia, the Roman name for Paris.

Where does the name come from?

Lutetium comes from Lutetia, the Latin name of the ancient town that became Paris. French chemist Georges Urbain, who discovered the element in 1907, named it after his home city.

Discovery timeline