Periodic Table

Hydrogen

Nonmetal

Quick Facts about Hydrogen

  • gas- state of matter at room temperature
  • Stable- has at least one stable isotope
  • +1, -1- common oxidation states in compounds
  • HEX- crystal structure, atomic arrangement in solid form
He

Hydrogen (H) is element 1 on the periodic table. Atomic mass of H: 1.0080 u. H is in period 1, group 1. Melting point of H: 13.99 K.Density of H: 0.00 g/cm³.

Why Hydrogen Matters

You interact with hydrogen every time you drink water or fill up your car

In Your Home

  • Water (H2O) in every faucet and glass
  • Natural gas for heating and cooking (methane is CH4)
  • Hydrogen peroxide in your medicine cabinet
  • Plastics, fabrics, and food all contain hydrogen

Industry Uses

AerospaceLiquid hydrogen powers rockets (NASA's Space Launch System)
AgricultureAmmonia production for fertilizers (Haber process)
EnergyHydrogen fuel cells for zero-emission vehicles
PetroleumHydrocracking to refine crude oil into gasoline

In Your Body

✓ Essential for life

Component of water and all organic molecules. Makes up ~10% of human body mass. Essential for DNA, proteins, fats, and carbohydrates.

Safety: Non-toxic in water or organic compounds. Pure H2 gas is non-toxic but highly flammable.

Discovery of Hydrogen

Discovered by Henry Cavendish in England, 1766

Name origin: Greek: hydro (water) and genes (generate)

History & Events

1766
Discovery
Henry Cavendish isolated hydrogen and called it 'inflammable air'
1937
Hindenburg Disaster
Hydrogen-filled airship caught fire in New Jersey, killing 36 and ending the airship era
1969
Apollo 11 Moon Landing
Hydrogen-oxygen rockets powered the first humans to the Moon
2020
Hydrogen Economy Push
EU and Japan announced major hydrogen energy initiatives for clean transportation

About Hydrogen

Colorless, odorless gaseous chemical element. Lightest and most abundant element in the universe. Present in water and in all organic compounds. Chemically reacts with most elements. Discovered by Henry Cavendish in 1776.

Atomic Properties of H

Atomic Number of H
1
Atomic Mass of H
1.0080 u
Electron Configuration
1s1
Electronegativity
2.20
Block
s-block
Group
1
Period
1

Physical Properties of H

Phase (STP)
gas
Melting Point of H
13.99 K
Boiling Point of H
20.27 K
Density of H
0.0001 g/cm3

Thermal Properties

Heat of Fusion
0.12 kJ/mol
Heat of Vaporization
0.90 kJ/mol
Specific Heat
14.30 J/g·K
Molar Heat Capacity
28.84 J/mol·K
Thermal Conductivity
0.18 W/m·K

Atomic Radii

Calculated
25 pm
Covalent
32 pm
Van der Waals
110 pm

Common Misconceptions

Wrong:Hydrogen is always a gas.
Correct:At -253°C, hydrogen becomes liquid. At -259°C, it becomes solid. Liquid hydrogen is used as rocket fuel.
Wrong:Water is hydrogen.
Correct:Water is H2O—hydrogen bonded to oxygen. Pure hydrogen is H2, a colorless gas.
Wrong:Hydrogen cars run on water.
Correct:Hydrogen fuel cells use H2 gas, not water. They produce water as exhaust, but need hydrogen fuel.

Isotopes of Hydrogen

Hydrogen has 2 naturally occurring isotopes, plus 1 notable radioactive isotope.

IsotopeAtomic Mass (u)AbundanceHalf-LifeDecay Mode
11H (H-1)Hydrogen-1 isotope1.00782503299.99%
21H (H-2)Deuterium, DHydrogen-2 isotope2.0141017780.0115%
31H (H-3)Tritium, THydrogen-3 isotope3.0160492780%12.32 yearsβ⁻

Data source: NIH PubChem (aggregated from IUPAC, NIST)

Isotope Applications

Isotopes of Hydrogen have important real-world applications in science and industry.

Geochronology & Dating

3H (tritium), with a half-life of 12.31 years, decays to 3He. The relative variations in n(3He)/n(3H) ratios can be interpreted in terms of elapsed time for dating purposes. The dates of groundwater recharge (water moving downward from the surface), where large amounts of 3H were received from precipitation following thermonuclear bomb test periods, come from the elapsed time since a water mass became isolated from the atmosphere in the time range from the mid-1950s to the present [15].

Industrial Applications

3H is used for self-luminous exit signs in aircraft and commercial buildings. It is found in luminous dials, gauges, wristwatches, and luminous paints [22]. 2H, in the form of heavy water, is used in CANDU (CANada Deuterium Uranium) nuclear reactors as a moderator and coolant [23].

Medical Applications

2H is used for the isotopic labeling of drugs and nutrients to trace their uptake and metabolism in the human body [24], [25]. 2H, in the form of heavy water, is used to study human metabolism. For example, 2H is used in combination with 18O (double labeled water) to measure energy expenditure [26].

Abundance

Earth's Crust
1.4 g/kg
Seawater
108.0 g/kg

Uses

Most hydrogen is used in the production of ammonia. Also used in balloons and in metal refining. Also used as fuel in rockets. Its two heavier isotopes are: deuterium (D) and tritium (T) used respectively for nuclear fission and fusion.

Sources

Commercial quantities are produced by reacting superheated steam with methane or carbon. In lab work from reaction of metals with acid solutions or electrolysis.

Geochemistry

Goldschmidt
atmophile
Geochemical Class
volatile

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