Cerium (Ce)
Element 58 · Lanthanide · atomic mass 140.12 u · f-block, period 6
Electron shells: 2, 8, 18, 19, 9, 2
Cerium is the most abundant rare earth, about as common as copper. It flips easily between two oxidation states, which makes it a superb oxygen-shuttling catalyst.
The spark from a cigarette lighter is burning cerium alloy shaved off by the flint wheel.
- Atomic number
- 58
- Atomic mass
- 140.12 u
- Electron configuration
- [Xe] 6s² 4f¹ 5d¹
- Group · period · block
- f-block · 6 · f
- Oxidation states
- +3, +4
- Electronegativity
- 1.12 (Pauling)
- Melting point
- 798 °C
- Boiling point
- 3,424 °C
- Density
- 6.77 g/cm³
- State at 20 °C
- Solid
- Appearance
- Silvery-white, soft metal
- Discovered
- Martin Heinrich Klaproth, Jöns Jacob Berzelius and Wilhelm Hisinger, 1803
58 protons, and 58 electrons when neutral
IUPAC standard atomic weight
Shown in the strip below the table
What Cerium is used for
- Catalytic converter oxygen storage
- Glass and silicon wafer polishing
- Lighter flints (ferrocerium)
- Self-cleaning oven coatings
Atomic structure of Cerium
A neutral cerium atom has 58 protons and 58 electrons. Its most common isotope carries about 82 neutrons, which is where the mass number 140 comes from. Change the neutron count and you have a different isotope of cerium; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 19, 9, 2. In orbital notation that is [Xe] 6s² 4f¹ 5d¹. As a f-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Cerium's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Cerium sits in the periodic table
The first f-block row, elements 57-71. Chemically near-identical to each other and hard to separate, yet essential to magnets, lasers and phosphors.
- One proton lighter: Lanthanum.
- One proton heavier: Praseodymium.
Discovery and naming
Cerium was discovered by Martin Heinrich Klaproth, Jöns Jacob Berzelius and Wilhelm Hisinger in 1803. Its name comes from The dwarf planet Ceres.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Cerium?
The standard atomic weight of Cerium is 140.12 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Cerium have?
Cerium has 58 protons, because the atomic number is the proton count and that is what makes an atom Cerium at all. A neutral Cerium atom has the same number of electrons, 58. The neutron count varies by isotope; the most common one has about 82, since 140 − 58 = 82.
What is the electron configuration of Cerium?
The electron configuration of Cerium is [Xe] 6s² 4f¹ 5d¹. Its electrons are arranged 2, 8, 18, 19, 9, 2 across 6 shells.
Is Cerium a metal?
Yes. Cerium is classified as a lanthanide, on the metallic side of the table.
What group and period is Cerium in?
Cerium sits in the f-block strip below the main table, in period 6, among the lanthanides. Elements in that strip are not given a group number in the standard 18-column layout.
What is the charge of Cerium?
Cerium most commonly forms a 3+ or 4+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Cerium?
Cerium melts at 798 °C and boils at 3,424 °C. That puts it in the solids at everyday temperatures.
What is Cerium used for?
Catalytic converter oxygen storage, Glass and silicon wafer polishing, Lighter flints (ferrocerium), Self-cleaning oven coatings. Cerium is the most abundant rare earth, about as common as copper.
Who discovered Cerium, and where does its name come from?
Cerium (Ce) was discovered by Martin Heinrich Klaproth, Jöns Jacob Berzelius and Wilhelm Hisinger in 1803. The name comes from The dwarf planet Ceres.