Page 26 - Curriculum Visions Dynamic Book

Sr see Strontium Strontium (Sr)
Element 38. A soft, lead-like metal in group 2 (the alkaline-earths) in the Periodic Table. It is softer than calcium and more reactive, decomposing quickly in water. Its silvery surface, when freshly cut, rapidly tarnishes to a yellow oxide. A powder of strontium ignites spontaneously in air. Strontium compounds turn flames
Key facts...
Name: strontium
Symbol: Sr
Atomic number: 38
Atomic weight: 87.62
Position in Periodic Table: group 2 (2)
(alkaline earth metal); period 5
State at room temperature: solid
Colour: silvery
Density of solid: 2.54 g/cc
Melting point: 769°C
Boiling point: 1,384°C
Origin of name: named after the village of
Strontian in Scotland
Shell pattern of electrons: 2–8–18–8–2
a crimson colour.
 Red strontium flame
Discovery
It was discovered in 1790 by Scottish scientists Adair Crawford and William Cruikshank in a new mineral strontianite (strontium carbonate, SrCO3). Strontium metal was isolated
by Sir Humphry Davy using electrical means in 1808.
Technology
Strontium produces the red colour in signal flares and fireworks. It is also used in glass for television tubes.
Geology
Strontium is not found as a native element, but it is mainly in strontianite and also as a result of nuclear explosions.
Biology
Strontium does not occur naturally in living things. However, because strontium and calcium are so similar,
and strontium is more reactive, any strontium in the environment will
be absorbed by the body and it will replace calcium in the bones.
Radioactive isotopes of strontium are produced during nuclear
explosions, and they are the main health hazard in radioactive fall-out. Strontium in the soil from the fall-out of the Chernobyl nuclear explosion in 1986 has resulted in many areas in northern Europe being unsuitable for farming.
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