What Is Cerium?
Cerium is a chemical element with the symbol Ce and atomic number 58, part of the lanthanide series of rare earth elements.
The most abundant rare earth metal. Used in catalytic converters and glass polishing.
As a lanthanide in Period 6 and Group 3 (Transition Metals), cerium's placement on the table reflects its electron configuration of [Xe] 4f¹ 5d¹ 6s², which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Cerium is located in Period 6, an unusually long row that includes the entire lanthanide series.
Within that row, cerium sits in Group 3 (Transition Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Cerium has an atomic mass of 140.116 u and a density of 6.770 g/cm³. Its melting point is 798°C and its boiling point is 3360°C.
Cerium displays the typical lanthanide combination of a silvery appearance and chemistry dominated by its f-orbital electrons.
Electron Configuration Explained
Cerium's electron configuration is [Xe] 4f¹ 5d¹ 6s², describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine cerium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Cerium was formally discovered in 1803, Berzelius, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Cerium Used For?
Cerium's specific properties make it useful in several applications, including:
- Catalytic converters
- Glass polishing
- Lighter flints
- Fluorescent lamps
- Self-cleaning ovens
These uses reflect cerium's underlying classification as a lanthanide, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Cerium
- Lighter flints are made from ferrocerium — an alloy containing about 50% cerium.
- Cerium is element number 58 on the periodic table, in Period 6 and Group 3.
- Its standard atomic mass is 140.116 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Cerium's atomic number?
Cerium has atomic number 58.
What is Cerium's chemical symbol?
Cerium's symbol is Ce.
What group and period is Cerium in?
Cerium is in Period 6, Group 3 (Transition Metals).
What is Cerium's atomic mass?
Cerium's standard atomic mass is 140.116 u.