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Periodic Table of Elements

Element Helium - He

Comprehensive data on the chemical element Helium is provided on this page; including scores of properties, element names in many languages, most known nuclides of Helium. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.

Helium Menu

• Helium Page One
  • Overview of Helium
  • Helium's Name in Other Languages
  • Atomic Structure of Helium
  • Chemical Properties of Helium
  • Physical Properties of Helium
  • Regulatory / Health
  • Who/When/Where/How
• Helium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides

Overview of Helium

• Atomic Number: 2
• Group: 18
• Period: 1
• Series: Noble Gasses

Helium's Name in Other Languages

• Latin: Helium
• Czech: Helium
• Croatian: Helij
• French: Hélium
• German: Helium - s
• Italian: Elio
• Norwegian: Helium
• Portuguese: Hélio
• Russian: Гелий
• Spanish: Helio
• Swedish: Helium

Atomic Structure of Helium

• Atomic Radius: 0.49Å
• Atomic Volume:
• Covalent Radius: 0.93Å
• Cross Section (Thermal Neutron Capture)σ_a/barns: 0.007
• Crystal Structure: Hexagonal

  

• Electron Configuration:

  1s²

• Electrons per Energy Level: 2

  Shell Model
  

• Ionic Radius:
• Filling Orbital: 1s²
• Number of Electrons (with no charge): 2
• Number of Neutrons (most common/stable nuclide): 2
• Number of Protons: 2
• Oxidation States: 0
• Valence Electrons: 1s²

  Electron Dot Model
  

Chemical Properties of Helium

• Electrochemical Equivalent:
• Electron Work Function:
• Electronegativity: N/A (Pauling); 5.5 (Allrod Rochow)
• Heat of Fusion: 5.23kJ/mol
• Incompatibilities:

• Ionization Potential
  • First: 24.587
  • Second: 54.416
• Valence Electron Potential (-eV):

Physical Properties of Helium

• Atomic Mass Average: 4.002602
• Boiling Point: 4.365K -268.785°C -451.813°F
• Coefficient of lineal thermal expansion/K^-1: N/A
• Conductivity

  Electrical:
  Thermal: 0.00152 W/cmK

• Density: 0.1785g/L @ 273K & 1atm
• Description:

  Light, odorless, colorless, tasteless noble gas.

• Enthalpy of Vaporization: 0.083 kJ/mole
• Flammablity Class: Non-flammable gas
• Freezing Point: see melting point
• Heat of Vaporization: 0.0845kJ/mol
• Melting Point: 1.1K -272.05°C -458°F
• Molar Volume: 31.8 cm³/mole
• Optical Refractive Index: 1.000035 (gas) 1.028 (liquid)
• Physical State (at 20°C & 1atm): Gas
• Specific Heat: 5.193J/gK

Regulatory / Health

• CAS Number
  • 7440-59-7 compressed helium
• UN/NA ID and ERG Guide Number
  • UN1046  / 121 compressed helium
  • UN1963  / 120 liquified helium
• RTECS: NH6520000
• NFPA 704
  • Health: 0
  • Fire: 0
  • Reactivity: 0
  • Special Hazard:
• OSHA Permissible Exposure Limit (PEL)
  • No limits set by OSHA
• OSHA PEL Vacated 1989
  • No limits set by OSHA
• NIOSH Recommended Exposure Limit (REL)
  • No limits set by NIOSH
• Routes of Exposure: Although a harmless gas, helium may act as an asphyxiate if it excluded oxygen from lungs.
• Levels In Humans:
  Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
  • Blood/mg dm^-3: trace
  • Bone/p.p.m: nil
  • Liver/p.p.m: nil
  • Muscle/p.p.m: nil
  • Daily Dietary Intake: n/a
  • Total Mass In Avg. 70kg human: n/a

Who / Where / When / How

• Discoverer: Sir William Ramsey, Nils A. Langet, P.T.Cleve
• Discovery Location: London England/Uppsala Sweden
• Discovery Year: 1895
• Name Origin:

  Greek: hêlios (sun).

• Abundance of Helium:
  • Earth's Crust/p.p.m.: 0.008
  • Seawater/p.p.m.: 0.000004
  • Atmosphere/p.p.m.: 5.2
  • Sun (Relative to H=1E¹²): 6.31E+10
• Sources of Helium:

  Found in natural gas deposits (up to 7% helium) & in the air (5 parts per billion) Constantly lost to space; replenished by radioactive decay (alpha particles). Helium is the second most abundant element in the universe by mass (25%). World wide commercial production is around 4,500 tons per year.

• Uses of Helium:

  Used in balloons, deep sea diving & welding. Also used in very low temperature research and nuclear power plant coolant. Future possible uses include use as coolant for nuclear fusion power plants and in superconducting electric systems.

• Additional Notes:

  Helium has the lowest melting and boiling point of any element. Liquid Helium is called a "quantum fluid" as it displays atomic properties on a macroscopic scale. The viscosity of liquid helium is 25 micropoises (water has a viscosity of 10,000 micropoises). As helium is cooled below its transition point, it has an unusual property of superfluidity with a viscosity approaching zero micropoises. In addition, liquid helium has extremelyhigh thermal conductivity.

Helium Menu

• Helium Page One
  • Overview of Helium
  • Helium's Name in Other Languages
  • Atomic Structure of Helium
  • Chemical Properties of Helium
  • Physical Properties of Helium
  • Regulatory / Health
  • Who/When/Where/How
• Helium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides

References

A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

Related Resources

• Anatomy of the Atom
  Answers many questions regarding the structure of atoms.
• Molarity, Molality and Normality
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• Molar Mass Calculations and Javascript Calculator
  Molar mass calculations are explained and there is a JavaScript calculator to aid calculations.
• Chemical Database
  This database focuses on the most common chemical compounds used in the home and industry.

Citing this page

If you need to cite this page, you can copy this text:

Kenneth Barbalace. Periodic Table of Elements - Helium - He. EnvironmentalChemistry.com. 1995 - 2025. Accessed on-line: 1/28/2025
https://EnvironmentalChemistry.com/yogi/periodic/He.html
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