1. Hydrogen and Helium: Unique among elements for 2 reasons 99% of Universe (76% H 2 and 23% He) They can occupy 2 columns Hydrogen – group 1 and 17 Helium – group 2 and 18

2. Hydrogen was prepared many years before it was recognized as a distinct substance by Cavendish in 1766. It was given its name by Lavoisier in 1783.CavendishLavoisier The name is derived from the Greek words, hydro and genes, meaning water forming; the symbol H is derived from the name. Hydrogen is the most abundant element in the universeabundant element in the universe

3. Hydrogen: Liquid H 2 is used as a fuel in the Space Shuttle.Space Shuttle Liquid hydrogen is important in cryogenics and in the study of super- conductivity as its boiling point is only a few degrees above absolute zero. Great quantities of hydrogen are required commercially for the fixation of nitrogen from the air in the Haber ammonia process and for the hydrogenation of fats and oils. It is also used in large quantities in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization.Haber It is used as a rocket fuel, for welding, for production of hydrochloric acid, for the reduction of metallic ores, and for filling balloons. At one time hydrogen was used for dirigibles (blimps), but because it is inflammable,(think Hindenburg) the inert gas helium is preferred. Production in the U.S. alone now amounts to hundreds of millions of cubic feet per day.rocket fueldirigibles

4. Helium: The element was discovered by Ramsay in 1896.Ramsay The name is from the Greek word, helios, for the sun since the evidence of the existence of helium was first obtained by Janssen during the solar eclipse of 1868. He detected a new yellow line in the solar spectrum. Lockyer and Frankland suggested the name helium for the new element after determining that the spectral line was due to a previously unknown element.JanssenLockyerFrankland The helium content of the atmosphere is about 1 part in 200,000. However, the element is chemically inert, forming no true compounds.

5. Helium is widely used: as an inert gas shield for arc welding; as a lifting gas for balloons and blimps (being much safer than hydrogen);blimps as a protective gas in growing silicon and germanium crystals and in titanium and zirconium production; as a cooling medium for super-conducting magnets;super-conducting magnets as the medium in He-Ne lasers;lasers as a gas for supersonic wind tunnels. A mixture of 80% helium and 20% oxygen is used as an artificial atmosphere for divers and others working under pressure. Since helium is less soluble in the blood than nitrogen and does not produce the "bends," a painful condition caused by the formation of bubbles of gas in the bloodstream when a diver comes to the surface

6. Alkali Metals: Group 1 or IA Soft, low melting points, low density, very reactive with water both in liquid form and in the air. (must store in oil) Oxidation occurs quickly when exposed to oxygen.

7. Lithium: