Hydrogen

Hydrogen is the first element of the Periodic table, and is represented by the symbol H. It is the lightest element, weighing on average 1.00794 amu (atomic mass units), and it mostly consists of one proton and one electron, with no neutrons. It bonds with almost every other element of the periodic table, and is the most important component of organic matter, after carbon.

The discovery of hydrogen

Hydrogen gas was first artificially synthesized by Phillip von Hohenheim (known as Paracelsus) by mixing metals with strong acids. He was unaware that the flammable gas produced by this chemical reaction was a new chemical element. In 1671, Robert Boyle rediscovered the reaction between iron and diluted acids, which results in the production of hydrogen gas. He noted that these fumes were highly flammable and that the flame gave off a lot of heat, but not much light.
In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by identifying the gas from a metal-acid reaction as “flammable air”. In 1781 he was the first person to find that the gas produces water when burned. This was a key experiment in disproving the Aristotelian theory of the four elements. As a consequence of his work he is given credit for its discovery as an element but it was Antoine Lavoisier who in 1783 named the element hydrogen (from the Greek hydro meaning water and genes meaning creator) after he reproduced Cavendish's findings.

Hydrogen Isotopes

Hydrogen exists as three known isotopes: protium, deuterium and tritium. Protium is the most abundant isotope, and it consists of only one proton and one neutron. Deuterium is the only other stable hydrogen isotope, with one proton and one neutron in its nucleus. Tritium is an unstable isotope with one proton and two neutrons in its nucleus, and is radioactive, with a half-life of 12.32 years. Other isotopes of hydrogen exist, but they are not observed in nature, they are synthesized in laboratories, are radioactive and have a very small half-life.

Hydrogen in compounds

As already stated, hydrogen bonds with almost all other chemical elements. In compounds, hydrogen can be positively or negatively charged, depending on the element it bonds with. Negatively charged hydrogens, known as hydrides, occur in ionic compounds with alkali and alkaline earth metals, compounds with d- and f-elements which have metal-like properties, and in covalent polymerized hydrides which have yet to be researched. Positively charged hydrogens, known as protons, (for they consist of only one proton and no electrons) are more common than hydrides, and occur with elements of higher electro negativity, (such as carbon, nitrogen, oxygen), halogen elements, and others. All of the bonds in these compounds are predominantly covalent, with a bigger or smaller ionic nature, depending on the element. Most of these compounds are gases or liquids at room temperature.

Hydrogen bonds

Hydrogen is the only element that can create unique bonds with other elements whereas other elements cannot create them, for they are a property of only hydrogen – hydrogen bonds. Hydrogen bonds are medium-strength (they have an energy of 5-30kJ/mole), non-covalent bonds that occur between the hydrogen attached to an electronegative atom of one molecule and an electronegative atom of a different molecule. Usually the electronegative atom is oxygen, nitrogen, or fluorine, with a partial negative charge, and the hydrogen has the partial positive charge. The electronegative atom must have one or more unshared electron pairs as in the case of oxygen and nitrogen, and has a negative partial charge. The hydrogen, which has a partial positive charge tries to find another atom of oxygen or nitrogen with excess electrons to share and is attracted to the partial negative charge. This forms the basis for the hydrogen bond. Hydrogen bonds are the main reason water is a liquid at room temperature. The polarity of the water molecule with the attraction of the positive and negative partial charges is the basis for the hydrogen bonding.

Uses of Hydrogen
Hydrogen can be used as an excellent fuel, because it produces large amounts of energy on combustion. It is considered a clean, environment friendly fuel as it produces only water vapor as an end product. The main uses of hydrogen fuel are as power resources for remote locations like submarines, remote weather stations, spacecrafts, etc. Liquid hydrogen is used as rocket fuel. Deuterium, an isotope of hydrogen is used as a fuel in nuclear reactors for nuclear fusion reactions.Due to its light weight, one of the main uses of hydrogen gas is in balloons. Today, meteorologists use it in weather balloons. These balloons carry necessary instruments high up in the air in order to record some vital information related to atmospheric conditions. During World War I, it was used in balloon airships or dirigibles but not anymore, as it is highly combustible and can create disasterous consequences.There are a wide range of industrial uses of hydrogen. For example, in chemical, food, paint, fertilizer and many more industries. In food industry, hydrogen is used to manufacture hydrogenated vegetable oils like butter, margarine, etc. In this process, vegetable oils are chemically treated with hydrogen in presence of nickel as a catalyst to produce the solidified fatty substances. In petrochemical industry, it is used for refining crude oils. In welding industry, the welding torches consist of hydrogen. In chemical industry, it is used as a reducing agent for extraction of metals from their ores.Hydrogen is required for the manufacturing of many important chemical compounds. One of them is ammonia which is used for making fertilizers. It is used for making different types of important acids such as hydrochloric acid as well as bases. It is used for production of methyl alcohol which is required in paints, varnishes, inks, etc. Another important compound of hydrogen is hydrogen peroxide. There are many uses of hydrogen peroxide in our homes. It can be used to heal up small cuts and wounds and as a disinfectant. There even are negative uses of hydrogen, and such an example would be in nuclear warfare. The infamous hydrogen bomb, or H-bomb is a weapon that derives its energy from the nuclear fusion of hydrogen isotopes. The hydrogen bomb fuses, or joins together, lighter elements creating heavier elements. The end product weighs less than its components, and the difference is released as energy. Because extremely high temperatures are required in order to initiate fusion reactions, the hydrogen bomb is also known as a thermonuclear bomb.