Hydrogen is a chemical element with symbol H and atomic number 1. Classified as a nonmetal, hydrogen is a gas at room temperature. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass. Hydrogen is estimated to make up more than 90% of all the atoms three quarters of the mass of the universe! This element is found in the stars, and plays an important part in powering the universe through both the proton-proton reaction and carbon-nitrogen cycle. Stellar hydrogen fusion processes release massive amounts of energy by combining hydrogens to form helium. Hydrogen is the primary component of Jupiter and the other gas giant planets. At some depth in the planet’s interior the pressure is so great that solid molecular hydrogen is converted to solid metallic hydrogen. In 1973, a group of Russian experimenters may have produced metallic hydrogen at a pressure of 2.8 Mbar. At the transition the density changed from 1.08 to 1.3 g/cm3. Earlier, in 1972, at Livermore, California, a group also reported on a similar experiment in which they observed a pressure-volume point centered at 2 Mbar. Predictions say that metallic hydrogen may be metastable; others have predicted it would be a superconductor at room temperature.
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery-grey, ductile, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) somewhat stabilizes the free metal against further oxidation. Vanadium is a trace element that exists in multiple oxidation states and forms complexes with proteins. Vanadium has not been shown to be an essential element and, indeed, is absorbed poorly. No deficiency state of vanadium has been demonstrated in humans. High doses of vanadium are toxic to animals and can cause neurologic, hematologic, renal and hepatic toxicity. Feeding of high doses to humans causes gastrointestinal upset, but vanadium has not been linked to hepatotoxicity due to dietary intake or environmental exposures in humans. Vanadium is a compound that occurs in nature as a white-to-gray metal, and is often found as crystals. Pure vanadium has no smell. It usually combines with other elements such as oxygen, sodium, sulfur, or chloride. Vanadium and vanadium compounds can be found in the earth’s crust and in rocks, some iron ores, and crude petroleum deposits. Vanadium is mostly combined with other metals to make special metal mixtures called alloys. Vanadium in the form of vanadium oxide is a component in special kinds of steel that is used for automobile parts, springs, and ball bearings. Most of the vanadium used in the United States is used to make steel. Vanadium is also mixed with iron to make important parts for aircraft engines. Small amounts of vanadium are used in making rubber, plastics, ceramics, and other chemicals.