Hydrogen

Properties

Atomic number

1

Atomic mass

1.008 u

Category

Reactive Nonmetal

Group

1

Period

1

Block

s-block

Electron configuration

1s¹

Phase at STP

Gas

Density

0.08988 g/L

Melting point

13.99 K (-259.2 °C)

Boiling point

20.27 K (-252.9 °C)

Electronegativity

2.2

Atomic radius

53 pm

Ionization energy

13.598 eV

Discovery

1766 · Henry Cavendish

Compounds you can make with hydrogen

Hydrogen appears in 30 compounds in our periodic table sandbox. Each one is a real substance with its true chemical formula — combine the right elements in the right ratio below to discover it.

• H₂O

  Water

  The most essential compound for life, covering 71% of Earth’s surface.

• NH₃

  Ammonia

  A sharp-smelling gas, the backbone of nitrogen fertilizers that feed the world.

• CH₄

  Methane

  The simplest hydrocarbon and the main component of natural gas.

• H₂

  Hydrogen Gas

  The lightest and most abundant element in the universe, in its molecular form.

• HCl

  Hydrogen Chloride

  Dissolved in water it becomes hydrochloric acid, found in your stomach.

• NaOH

  Sodium Hydroxide (Lye)

  A strong base used in soap-making, drain cleaner, and paper production.

• H₂SO₄

  Sulfuric Acid

  A dense, oily acid and one of the most produced industrial chemicals on Earth.

• HNO₃

  Nitric Acid

  A powerful acid used to make fertilizers and explosives.

• H₂O₂

  Hydrogen Peroxide

  A reactive cousin of water, used as a disinfectant and bleaching agent.

• CH₄O

  Methanol

  The simplest alcohol, used as fuel, solvent, and antifreeze.

• H₂S

  Hydrogen Sulfide

  A toxic gas famous for its rotten-egg odor, produced by decaying matter.

• C₆H₁₂O₆

  Glucose

  A simple sugar and the primary energy source for living cells.

• C₂H₆O

  Ethanol

  The alcohol found in beverages, also used as fuel and disinfectant.

• PH₃

  Phosphine

  A toxic, flammable gas with a garlic-like odor.

• HF

  Hydrogen Fluoride

  Forms hydrofluoric acid, uniquely able to dissolve glass.

• NaHCO₃

  Sodium Bicarbonate (Baking Soda)

  Baking soda — a mild base used in cooking, cleaning, and antacids.

• C₂H₂

  Acetylene

  A hydrocarbon that burns hot enough to cut and weld steel.

• NH₄Cl

  Ammonium Chloride

  A salt used in batteries, fertilizer, and as a food additive (salty licorice).

• H₃PO₄

  Phosphoric Acid

  A mild acid that gives cola its tang and is used in rust removal.

• LiH

  Lithium Hydride

  A lightweight compound used as a hydrogen store and in nuclear shielding.

• KOH

  Potassium Hydroxide (Caustic Potash)

  A powerful base used to make soft soaps, biodiesel, and alkaline batteries.

• Ca(OH)₂

  Calcium Hydroxide (Slaked Lime)

  Slaked lime, used in mortar, plaster, and to treat acidic soil and water.

• NH₄NO₃

  Ammonium Nitrate

  A high-nitrogen fertilizer that is also a powerful industrial explosive.

• HCN

  Hydrogen Cyanide (Prussic Acid)

  A fast-acting poison with a faint almond smell, used industrially in tiny amounts.

• C₂H₄O₂

  Acetic Acid (Vinegar)

  The acid that gives vinegar its sour taste and sharp smell.

• H₂CO₃

  Carbonic Acid

  The weak acid formed when CO₂ dissolves in water — the fizz in soda.

• CH₂O

  Formaldehyde

  A pungent gas used to make resins and, in solution, to preserve biological specimens.

• C₆H₆

  Benzene

  A ring-shaped hydrocarbon, the foundation of "aromatic" chemistry.

• C₃H₈

  Propane

  A three-carbon hydrocarbon burned in barbecues, heaters, and camping stoves.

• HBr

  Hydrogen Bromide

  A sharp-smelling gas that dissolves in water to make hydrobromic acid.

Try it yourself: the hydrogen sandbox