Page 43 - Curriculum Visions Dynamic Book

Cl see Chlorine; Cm see Curium Cobalt (Co)
Element 27.A hard, brittle, magnetic transition metal. It is poorly reactive and resists oxidation.The distinctive blue colour of cobalt compounds has been used since ancient times.
Cobalt is a scarce metal and usually found as a trace element among ores of other elements such as iron and zinc. Cobalt is very reactive, and finely divided cobalt ignites spontaneously.
Cobalt is both magnetic and has
a high melting point, and so can be used where magnetism is required in a hot environment.
Cobalt-60 is a radioactive isotope and a source of gamma rays.
Discovery
Known about as a compound since ancient times, cobalt was first isolated as an element in 1735 by Swedish chemist Georg Brandt.
Technology Geology
The main use of cobalt is as a metal Cobalt is never found as a native metal. Many
Key facts...
Name: cobalt
Symbol: Co
Atomic number: 27
Atomic weight: 58.93
Position in Periodic Table: transition metal,
group (9) (cobalt group); period 4 State at room temperature: solid Colour: lustrous, metallic grey Density of solid: 8.9 g/cc
Melting point: 1,495°C
Boiling point: 2,870°C
Origin of name: from the German word kobald,
meaning goblin
Shell pattern of electrons: 2–8–15–2
in alloys, both for high temperature sulphide and arsenide ores contain cobalt.
permanent magnets and for making The main ore is Co S , cobaltite. However, very hard steels.Alnico is an alloy of 34
iron, nickel and cobalt that has a high magnetic strength. Cobalt also gets used in electroplating because it is hard and resists tarnishing. Cobalt phosphate is
a blue colouring agent in ceramics and glass. Radioactive isotopes of cobalt have medical applications and are also used to help detect flaws in materials.
it only occurs in small quantities. Cobalt is normally recovered as a by-product of refining ores of non-ferrous metals.
Biology
Cobalt is an essential element in blood cells as vitamin B12. Some concentrated meat products that go into drinks contain cobalt to add B12 to the diet.
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