Element Information, Facts, Properties, Trends, Uses, Comparison with other elements
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the Noble Gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.
It belongs to group 18 of the periodic table having trivial name noble gases, aerogens.
Read key information and facts about element Helium
|Phase||Gas (Monoatomic Gas )|
|Appearance||colorless gas, exhibiting a red-orange glow when placed in a high-voltage electric field|
|Group in Periodic Table||18|
|Group Name||helium family or neon family|
|Period in Periodic Table||period 1|
|Block in Periodic Table||p -block|
|Electronic Shell Structure (Electrons per shell)||2|
|Melting Point||0 K|
|Boiling Point||4.22 K|
How to Locate Helium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 2 to find Helium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Helium on periodic table look for cross section of group 18 and period 1 in the modern periodic table.
The element Helium was discovered by P. Janssen and N. Lockyer in year 1868 in Sweden and United Kingdom. Helium was first isolated by W. Ramsay,T. Cleve, and N. Langlet in 1895. Helium derived its name from the Greek word helios, meaning 'sun'.
Janssen and Lockyer observed independently a yellow line in the solar spectrum that did not match any other element. Years later, Ramsay, Cleve, and Langlet observed independently the element trapped in cleveite about the same time.
Helium Presence: Abundance in Nature and Around Us
The table below shows the abundance of Helium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|ppb by weight (1ppb =10^-7 %)||ppb by atoms (1ppb =10^-7 %)|
|Abundance in Universe||230000000||72000000|
|Abundance in Sun||230000000||74000000|
|Abundance in Meteorites||-||-|
|Abundance in Earth's Crust||5.5||30|
|Abundance in Oceans||0.0072||0.011|
|Abundance in Humans||-||-|
Crystal Structure of Helium
The solid state structure of Helium is Face Centered Cubic.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
|424.2 pm||424.2 pm||424.2 pm|
and the angles between them Lattice Angles (alpha, beta and gamma).
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
|Space Group Name||Fm_ 3m|
|Oxidation States||Space Group Number||225|
|Crystal Structure||Face Centered Cubic|
Helium Atomic and Orbital Properties
Helium atoms have 2 electrons and the electronic shell structure is  with Atomic Term Symbol (Quantum Numbers) 1S0.
|Number of Electrons (with no charge)||2|
|Number of Protons||2|
|Number of Neutrons||2|
|Shell structure (Electrons per energy level)||2|
|Main Oxidation States||-|
|Atomic Term Symbol (Quantum Numbers)||1S0|
Bohr Atomic Model of Helium - Electrons per energy level
Ground State Electronic Configuration of Helium - neutral Helium atom
Abbreviated electronic configuration of Helium
The ground state abbreviated electronic configuration of Neutral Helium atom is 1s2. The portion of Helium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as . For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 1s2, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Helium
Complete ground state electronic configuration for the Helium atom, Unabbreviated electronic configuration
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.
Atomic Structure of Helium
Helium atomic radius is 31 pm, while it's covalent radius is 32 pm.
|Atomic Radius Calculated|
31 pm (0.31 Å)
|Atomic Radius Empirical|
120 pm (1.2 Å)
|Atomic Volume||22.4136 cm3/mol|
|Covalent Radius||32 pm (0.32 Å)|
|Van der Waals Radius||140 pm|
|Neutron Cross Section||0.007|
|Neutron Mass Absorption||0.00001|
Atomic Spectrum of Helium
Helium Chemical Properties: Helium Ionization Energies and electron affinity
The electron affinity of Helium is 0 kJ/mol.
Ionization Energy of Helium
Refer to table below for Ionization energies of Helium
|Ionization energy number||Enthalpy - kJ/mol|
Helium Physical Properties
Refer to below table for Helium Physical Properties
|Molar Volume||22.4136 cm3/mol|
Hardness of Helium - Tests to Measure of Hardness of Element
Helium Electrical Properties
Helium is Conductor of electricity. Refer to table below for the Electrical properties ofHelium
Helium Heat and Conduction Properties
|Thermal Conductivity||0.1513 W/(m K)|
Helium Magnetic Properties
|Mass Magnetic Susceptibility||-5.9e-9 m3/kg|
|Molar Magnetic Susceptibility||-2.36e-11 m3/mol|
|Volume Magnetic Susceptibility||-1.05e-9|
Optical Properties of Helium
Acoustic Properties of Helium
|Speed of Sound||970 m/s|
Helium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Helium
|Melting Point||0 K (-273.15°C, -459.66999999999996 °F)|
|Boiling Point||4.22 K (-268.93°C, -452.0739999999999 °F)|
|Critical Temperature||5.19 K|
Enthalpies of Helium
|Heat of Fusion||0.02 kJ/mol|
|Heat of Vaporization||0.083 kJ/mol|
|Heat of Combustion||-|
Helium Isotopes - Nuclear Properties of Helium
Helium has 8 isotopes, with between 3 and 10 nucleons. Helium has 2 stable naturally occuring isotopes.
Isotopes of Helium - Naturally occurring stable Isotopes: 3He, 4He.
|Isotope||Z||N||Isotope Mass||% Abundance||T half||Decay Mode|