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Hydrogen, , Dihydrogen: Preparation, , Hydrogen is the most abundant element in the universe., It has three isotopes — protium, deuterium and tritium., , In spite of its resemblance to both alkali metals and halogens, it occupies a separate place in the, periodic table due to its unique behavior., , Its unique behavior also makes it a commercially important element., , In the laboratory, it is prepared by the reaction of zine with dilute hydrochloric acid or with, aqueous alkali., , Commercially, it is usually obtained from petro-chemicals, coal and by the electrolysis of aqueous, solutions., , Dihydrogen: Properties and Uses, , Dihydrogen is a colourless, odourless, tasteless, non-poisonous gas., The small size of hydrogen atoms is responsible for its unique properties., Dihydrogen gas is inert at room temperature., , Dihydrogen gas reacts with metals and non-metals at high temperatures forming the, corresponding hydrides.