Hydrogen (H)

by Mrs. Hooper

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Hydrogen is the first element on the Periodic Table and the most abundant element in the universe. Approximately 75% of the visible universe is Hydrogen, and up to 90% of the atoms in the universe are Hydrogen.

On Earth, Hydrogen exists mainly as the compound water. The picture above shows ionized Hydrogen in the Triangulum Galaxy, where charged gas particles undergo nuclear fusion to form stars.

Physicists love Hydrogen. Its atomic number of 1 means it has 1 proton in the nucleus and 1 electron orbiting the nucleus. This makes the Hydrogen atom the only atom for which complex quantum mechanical formulas work perfectly.

History of Hydrogen

Officially, Hydrogen was discovered in 1766 by Henry Cavendish. But he only gets the credit because two others dropped the ball. An alchemist named Paracelsus (in the 1500s) and a scientist named Robert Boyle (in 1671) both saw flammable bubbles form when iron and sulfuric acid reacted. Neither of them followed up on it, though, so Cavendish gets the glory.

Cavendish collected the bubbles and showed that those bubbles were different than other gases. He also showed that hydrogen burning (in oxygen) formed water. This experiment showed that water isn’t its own element; it’s made of hydrogen and oxygen.

The gas was named "water former" by Antoine Lavoisier. In Greek, "hydro" means "water" and "genes" means "former."


With a melting point of 14 Kelvin and a boiling point of 20 Kelvin, elemental Hydrogen is most often encountered as a colorless, odorless gas. Metallic Hydrogen can be formed at extremely high pressures, but otherwise conductivity and malleability are irrelevant when it comes to Hydrogen. At 0.0899 grams-per-liter, Hydrogen is the least dense of all gases.

Hydrogen's chemical properties are more important. Hydrogen is very reactive, combining rapidly with oxygen. Hydrogen is also highly flammable in the presence of oxygen.


Because it is lighter and cheaper than Helium, one of Hydrogen's early uses was for filling balloons and blimps.

This was soon found to be a bad idea because of how violently Hydrogen reacts with oxygen, as illustrated by the famous Hindenberg explosion.

[HQ] 1937 Hindenburg Explosion In Colour With Herbert Morrison's Commentary
Whoopsies. Big mistake to fill a blimp with Hydrogen gas.


The glass industry makes use of Hydrogen as a protective surrounding for making flat sheets of glass, and the electronics industry employs Hydrogen as a flushing gas to remove impurities from silicon chips.

The reason why our Sun shines is because stars are constantly turning the Hydrogen isotopes Deuterium and Tritium into Helium atoms through nuclear fusion, a process that releases insane amounts of energy.

In addition to providing energy through nuclear fusion, Hydrogen could also be a possible "clean" source of energy for the future. Hydrogen fuel cells are pollution-free and result from turning water into hydrogen and then back into water. Hydrogen fuel cells now appear in some cars and buses.

The Space Shuttle Main Engine burned hydrogen with oxygen to produce explosive amounts of thrust to propel shuttles into orbit.

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Hydrogen compounds form the building blocks of all living things. Compounds of hydrogen, carbon, and oxygen include carbohydrates (like sugars in fruit and candy) and lipids (like the fats and oils that make salad dressing and margarine). Hydrogen bonds with carbon, oxygen, and nitrogen to form proteins (which are responsible for structure and function in cells and allow our genes, like our hair or eye color, to be expressed). Hydrogen combines chemically with carbon, oxygen, nitrogen, and phosphorous to form nucleic acids (DNA and RNA). Carbohydrates, lipids, proteins, and nucleic acids are the biological macromolecules essential for life.

Hydrogen also bonds with oxygen to form water, which is essential for life.

Long chains of hydrogen and carbon called polymers form plastics and pharmaceuticals.

Hydrogen and nitrogen form the compound ammonia, which is a main ingredient in fertilizer.

Hydrogen itself is also an essential component in acids like hydrocholoric acid (HCl). Hydroxide ions (one hydrogen and one oxygen bonded together with an overall negative charge) form bases like sodium hydroxide (NaOH).


Hydrogen has two main isotopes, and they have special names based on their mass numbers. Deuterium is the special name for hydrogen-2, which has 1 proton and 1 neutron in the nucleus. Tritium is the special name for hydrogen-3, which has 1 proton and 2 neutrons in the nucleus.

Tritium is luminous and can be used to make light-up keychains or self-illuminating watches, commonly worn by scuba divers so they can see underwater.

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Element Card: Gray, Theodore W. (2008). The Photographic Card Deck of the Elements.

Elements Book: Gray, Theodore W. (2009). The Elements: A visual exploration of every known atom in the universe. New York: Black Dog & Leventhal Publishers, Inc.

Los Alamos Periodic Table: http://periodic.lanl.gov/1.shtml

Royal Society of Chemistry Periodic Table: http://www.rsc.org/periodic-table/element/1/hydrogen