Helium

Helium DISCOVERY: A French astronomer, Pierre-Jules-C?sar Janssen (1824-1907), first obtained certainty for the existence of atomic occur 2 during the solar eclipse of 1868 in India when he notice a impertinently white-livered line (587.49 nm) in the solar spectrum very close to the yellow(a) sodium D-line. It was non possible to approach out this line in the laboratory. Sir Norman Lockyer (1836-1920), an face astronomer, recognised that no known component at that era gave this line and named the fragment atomic number 2 for the solarize. For many eld helium was regarded as an element that might exist on the sun although it was unknown on the Earth.

Spectroscopists at the time doubted the results concerning helium. nonetheless the claims initiated a search for the new element on artificial satellite earth. In 1895, Sir William Ramsay detect helium after treating cleveite, a uranium mineral, with mineral acids. Ramsey sent samples of the bollocks up to Sir William Crookes and Sir Norman Lockyer who set helium. It was discovered independ...If you want to get a full essay, range it on our website: Orderessay

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