The chemical formula for hydrogen gas is H2. Its molar mass is 2.016 grams per mole, and it exists as a gas at standard temperature and pressure, where its density is 0.09 grams per liter. Hydrogen's melting point is -43... More »

The formula for hydrogen sulfide is H2S. This molecule consists of two atoms of hydrogen bonded to one atom of sulfur. Hydrogen sulfide exists as a naturally occurring gas. More »

Hydrogen is a chemical element that is abundant in the universe and appears as a colorless and odorless gas. It was discovered in 1766 by an English scientist named Henry Cavendish, who observed that hydrogen burns and f... More » Science Chemistry Atoms & Molecules

H2 is the chemical formula for dihydrogen, also known as diatomic hydrogen, hydrogen gas and molecular hydrogen. This is the naturally existing form of elemental hydrogen. More »

Ammonia is the chemical name for the molecular formula NH3, which is a compound of nitrogen and hydrogen. It is also known by the name azane. More »

It takes only one atom to make hydrogen; however, hydrogen is commonly found as H2, meaning two atoms make up hydrogen. Because of this, hydrogen is known as a diatomic element. More »

The lightest element is hydrogen, H2, which is also the most common. Hydrogen is very reactive and forms water when it interacts with oxygen. More »