5. Hydrogen and Helium atom

Difference Between Helium and Hydrogen


Helium: Helium is an element having the atomic number 2 and is represented by the symbol He.

Hydrogen: Hydrogen is a chemical element having the atomic number 1 and is represented by the symbol H.

Atomic Number

Helium: The atomic number of helium is 2.

Hydrogen: The atomic number of hydrogen is 1.

Atomic Weight

Helium: The atomic weight of helium is 4.002602 amu.

Hydrogen: The atomic weight of hydrogen is 1.00794 amu.


Helium: Helium exists as a monatomic gaseous substance.

Hydrogen: Hydrogen exists as a diatomic gaseous molecule.

Oxidation States

Helium: Helium has only 0 oxidation state.

Hydrogen: Hydrogen has -1, 0 and +1 oxidation states.


Helium: Helium has two major isotopes as 3He and 4He.

Hydrogen: Hydrogen has three major isotopes; Protium, deuterium, and tritium.

Melting Point

Helium: The melting point of helium is -272.2oC.

Hydrogen: The melting point of hydrogen is -259oC.

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