Cerium Facts, Symbol, Discovery, Properties, Uses

Table Of Contents

What is Cerium
Where is Cerium Found
History
Cerium Identification
Properties and Characteristics of Cerium
Atomic Data of Cerium (Element 58)
What is It Used for
Cerium Toxicity
Interesting Facts
Cost of Cerium

What is Cerium

Cerium (pronunciation: SER-ee-em) is a soft, grayish metal that belongs to the group of lanthanides and is represented by the chemical symbol Ce ^{[1, 2]}. Its naturally-occurring isotopes include Cerium-136, Cerium-138, Cerium-140, and Cerium-142, out of which Cerium-140 is the most abundant (with 88.48% natural abundance) ^[3]. Among the 35 known radioisotopes of cerium, the most stable is Cerium-144 that is characterized by a half-life period of 284.893 days ^[3].

Where is Cerium Found

Cerium is commonly found in rare earth minerals like bastnaesite and monazite ^[1]. The mineral ore is heated and then treated with hydrochloric acid to produce cerium oxide from which metallic cerium is isolated through electrochemical reduction ^[1]. The metal can also be obtained through thermal reduction of cerium fluoride with calcium ^{[1, 4]}. While China, the CIS countries, and the USA have the highest cerium reserves, the top 3 cerium producing countries in the world are China, Russia, and Malaysia ^[1].

History

Origin of its Name: It is named after ‘Ceres’, an asteroid that was named after the Roman goddess of fertility and agriculture ^[1].

Who discovered it: The element was discovered by the Swedish chemists, Jöns Jacob Berzelius along with Wilhelm von Hisinger, and independently by the German chemist Martin Klaproth ^{[1, 4]}.

When and How was it Discovered

In 1803, Berzelius and Hisinger discovered the new element from a reddish-brown cerium salt called cerite ^{[1, 5]}. While investigating the chemical reaction of the cerium salts, they found the two oxidation states – one of which producing yellowish-red salts and the other colorless ones ^[5]. Although they did not isolate the pure form, they named the element ‘cerium’ and its oxide ‘ceria’ ^[5].

Martin Klaproth analyzed the salt and concluded that it consists of an oxide of a new metallic element ^[5]. He named the oxide ‘ockroite’ because of its yellowish-red color ^[5]. However, the result of Berzelius and Hisinger was published before that of Klaproth, and so the name cerium was approved ^[5].

Cerium Identification
Atomic number	58 ^[1]
CAS number	7440-45-1 ^[1]
Position in the periodic table	Group	Period	Block
	Lanthanides ^[1]	6 ^[1]	f ^[1]

Location of Cerium in the Periodic Table

Properties and Characteristics of Cerium

General Properties

Atomic mass

140.116 amu^[1]

Relative atomic mass

140.116 ^[1]

Physical Properties

Color

Gray ^{[1, 5]}

Melting point/freezing point

799 °C, 1470 °F ^[1]

Boiling point

3443 °C, 6229 °F ^[1]

Density

6.77 g cm^-3 ^[1]

State of matter at room temperature (solid/liquid/gas)

Solid ^{[1, 5]}

Hardness

– Brinell

412 MPa ^[6]

– Mohs

2.5 ^[6]

– Vickers

270 MPa ^[6]

Electrical conductivity

1.4X10⁶ S/m ^[6]

Thermal (heat) conductivity

11 W/(m K) ^[6]

Specific heat

192 J kg^-1 K^-1 ^[1]

Bulk modulus

21.5 GPa ^[1]

Shear modulus

13.5 GPa ^[1]

Young’s modulus

33.6 GPa ^[1]

Vapor pressure

– Temperature (K)

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

– Pressure (Pa)

–

2.47 X 10^-11

8.91 X 10^-8

2.97 X 10^-5

2.33 X 10^-3

6.91 X 10^-2

1.04

9.56

60.8

Chemical Properties

Oxidation state/Oxidation number

+2,+3, +4 ^[1]

Isotopes

Isotope

Mass

Abundance (%)

Half-life

Mode of decay

¹³⁶Ce

135.907

0.185

>0.7 X 10¹⁴ y

EC EC

>4.2 X 10¹⁵ y

β-β-

¹³⁸Ce

137.906

0.251

>3.7 X 10¹⁴ y

EC EC

¹⁴⁰Ce

139.905

88.45

–

¹⁴²Ce

141.909

11.114

>1.6 X 10¹⁷ y

β-β-

Atomic Data of Cerium (Element 58)

Valence electrons	2 ^[7]
Quantum numbers
– n	4 ^[7]
– ℓ	3 ^[7]
– m_ℓ	-2 ^[7]
– m_s	+1/2 ^[7]
Electron configuration (noble gas configuration)	[Xe] 4f¹5d¹6s^{2 [1]}
Atomic structure
– Number of electrons	58 ^[5]
– Number of neutrons	82 ^[5]
– Number of protons	58 ^[5]
Radius of Atom
– Atomic radius	2.42 Å ^[1]
– Covalent radius	1.84 Å ^[1]
Electronegativity (Pauling-scale)	1.12 ^[1]
Electron affinity	62.72 kJ mol^-1 ^[1]
Ionization energy (kJ mol^-1)	1st	2nd	3rd	4th	5th	6th	7th	8th
	534.403	1046.87	2697.73	3546.608	6324.61	7487.3	–	–

Cerium Electron Configuration (Bohr Model)

What is It Used for

The mischmetal alloy made of cerium, lanthanum, neodymium, and praseodymium mixed with magnesium oxide and iron oxide is used as flints for lighting cigarettes and gas ^{[1, 5]}.
Cerium oxide, as a catalyst, is used in self-cleaning ovens for preventing the accumulation of cooking residues and for polishing glass surfaces ^{[1, 5]}.
It is used in catalytic converters because it helps reduce automobile exhaust emissions ^[1]. Cerium oxide nanoparticles are added to diesel for reducing the emission of soot and improving engine performance of vehicles ^[5].
Cerium sulfide is non-toxic by nature and is used as a coloring pigment because of its rich red color ^[1].
The element is used in phosphors in flat-screen televisions, floodlights, and energy-efficient light bulbs ^[1].
Flammacerium, a compound containing cerium nitrate and silver sulfadiazine, is a topical ointment used for treating infections in burn wounds ^[5].

Cerium Toxicity

The element 58 has no known biological roles and is low to moderate in toxicity ^{[1, 5]}.

Interesting Facts

The image of cerium is a graphical representation of the asteroid Ceres, whereas the background is derived from an astronomical map of the 17th-century ^[1].
Its natural abundance is almost similar to zinc, but it is more than lead or tin ^[1].
At room temperature, the element can readily oxidize ^[4].
Pure cerium may ignite if scratched with a sharp metal object such as a knife ^[4].
It decomposes in water to produce cerium hydroxide and hydrogen ^[5].

Cost of Cerium

The cost of 100 grams of pure cerium is about $380, but in bulk, it is about $1.20 ^[5].

References