Hydrogen is sometimes called dihydrogen, molecular hydrogen, or hydrogen gas.

It is the lightest and simplest element on the periodic table and is the most common element found in the universe. Because it is so light, it easily escapes Earth’s gravity.

In stars, hydrogen is mostly in a plasma state.

Hydrogen was artificially produced by humans as early as the 16th century, when they began experimenting by reacting acids with metals.

In the late 18th century, Henry Cavendish was the first person to identify hydrogen as a unique, separate substance.

Hydrogen was once commonly used in balloons, but after the Hindenburg disaster, it was largely replaced by the much safer helium.

It is possible to fuel cars with hydrogen, and its only byproduct is water.

The name “hydrogen” comes from Greek words meaning “water former.” Despite hydrogen and oxygen being extremely flammable, their combined chemical formula—H₂O—is one of the least flammable substances imaginable.

In its purest form, hydrogen is odorless and invisible.

Hydrogen plays a key role in determining the acidity of a substance. In fact, “pH” stands for “potential of hydrogen.”