Cerium Element in Periodic Table | Atomic Number Atomic Mass
Cerium is the second chemical element in the Lanthanide series of the periodic table. It is represented by the symbol Ce and its atomic number is 58. Like its precursor lanthanum in the Lanthanide series, it is a silvery-white element, ductile and soft enough to be cut with a knife. When exposed to air, it gets tarnished into dark grey or black colour. It exhibits dual oxidation state of +3 and +4. It is followed by praseodymium and neodymium in succession in the Lanthanide series. Ce is a ductile metal akin to silver. Generally, lanthanide elements exhibit valency three; however, cerium shows exception due to the stability of empty f-shell in Ce+4.
There are four allotropes of cerium tagged by the names α, β, γ and δ. The allotropes are stable in different ranges of temperatures.
α- cerium ------------ stable below -150°C.
β – cerium ----------- stable between -150°C and approximately room temperature.
γ - cerium ----------- stable between room temperature and 726°C.
δ - cerium ----------- stable above 726°C.
There are four naturally occurring isotopes of cerium, viz., 136Ce, 138Ce, 140Ce and 142Ce, out of which 140Ce is most abundant. In addition to the naturally occurring isotopes, several artificial isotopes are synthesized for research purposes.
Ce is a highly electropositive element and reacts with water to form cerium hydroxide releasing hydrogen gas. Cerium metal reacts with halogens to form cerium trihalides.
Uses Of Cerium Element:
Ce metal and its compounds are used in a variety of applications. They are added to glass and ceramic materials to impart colours, to fade off the existing colours, to make glass sensitive to certain form of radiation, to strengthen certain forms of dental materials and to render optical (light) qualities to glass.
Hazards Of Cerium Element:
Cerium does not have appreciable biological role in humans. But vapours emanating from the ce fires are toxic. Water should not be used in extinguishing cerium fires because cerium reacts with water to release hydrogen gas which again is highly combustible. However, ce present in traces with calcium phosphate minerals in human bones is not considered jeopardous.
Cerium Element Information:
Discovery year: 1803
Discovered by:Martin Heinrich Klaproth, Jöns Jakob Berzelius, Wilhelm Hisinger
Atomic number: 58
Relative atomic mass: 140.116
Electron configuration: [Xe] 4f1 5d1 6s2
Other elements in the same block:
Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americium, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium and Lawrencium are the elements in the same block.
Period: period 6
Other elements in the same period:
Caesium, Barium, Lanthanum, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, Mercury, Thallium, Lead, Bismuth, Polonium, Astatine and Radon
Other elements in the same group:
Other elements in the same orbital:
Key isotopes: 140Ce
Melting point: 799°C, 1470°F, 1072 K
Boiling point: 3443°C, 6229°F, 3716 K
Element category: lanthanide
Density (g cm−3): 6.77
CAS number: 7440-45-1
Color: silvery white
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