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Elements

Elements. Alkaline Earth Metals. Strontium. Symbol Sr

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Elements

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  1. Elements Alkaline Earth Metals

  2. Strontium Symbol Sr Adair Crawford an Irish chemist discovered the element strontium in 1790. He mixed the mineral witherite (BaCO3) with Hydrochloric acid (HCl) and got unexpected results. He guessed the witherite was mixed with an unknown mineral that he named strontianite (SrCO3). Strontium is used to make picture tubes for coloured T.V. An isotope -atom that has the same number of protons but different number of neutrons-of this element called strontium-90 is a product of nuclear explosives and is especially dangerous because it is highly radioactive and when absorbed by the body new blood cells cannot be produced, which leads to death.

  3. Properties • Strontium is a silver –yellow colour. It reacts violently with water and tarnishes fast in air so it is stored out of contact with them. The natural occurrence of strontium is always combined with other elements for this reason. Finely powdered strontium metal will ignite immediately in air forming strontium oxide and strontium nitride

  4. Barium Symbol Ba Carl Scheele (left)discovered barium in 1774. But it was first extracted by Humphry Davy in 1808. Davy (right)extracted it through electrolysis-separating chemicals by passing an electric current through a liquid containing ions- of molten baryta. Heated Barium chloride is used for the production of white and green fireworks. Barium chloride is also used in rat poison because of its high toxicity. Barium’s most common use is in oil production. Barium sulfate is mixed with water and other minerals to make drilling mud. It is pumped into drilling holes and its weight prevents the oil from bursting out into the environment.

  5. Properties of barium • A silver-white metal that can be found combined with other chemicals like sulphur, carbon or oxygen. Barium oxidises quickly in the air. It reacts violently with water to form the hydroxide, liberating hydrogen. • Barium reacts with most non-metals and usually forms poisonous compounds. • It has 16 isotopes many of which are not put to use because of toxicity

  6. Radium • Symbol Ra • Discovered by Marie and Pierre Curie in 1898. Uranium was found to emit radiations. The Curies thought that pitchblende which is the ore of uranium contained radioactivity too. They refined it and finally succeeded in extracting 100 milligrams of radium from tonnes of pitchblende. Radium is much more powerful than uranium. • Radium 226 is used in medicine to destroy cancer growths.

  7. Properties • Pure radium is white and thousands of times more valuable than gold. There is very little pure radium in the world. If radium is handled carelessly its radioactive rays can cause radiation burns. • Radium has 16 isotopes the most common of which is radium 226.

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