• What Is The Mass Number Of Helium
• Atomic Number Of Helium

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.

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Atomic Number of Helium Helium is a chemical element with atomic number 2 which means there are 2 protons and 2 electrons in the atomic structure. The chemical symbol for Helium is He. The atom consist of a small but massive nucleus surrounded by a cloud of rapidly moving electrons. Gaseous chemical element, symbol: He, atomic number: 2 and atomic weight 4,0026 g/mol. Helium is one of the noble gases of group O in the periodic table. It’s the second lightest element. The main helium source in the world is a series of fields of natural gas in the United States. The atomic weight of helium is 4.002602, the average that reflects the typical ratio of natural abundances of its isotopes. Atomic weight is measured in atomic mass units (amu), also called daltons. See below for a list of chemical elements and their atomic weights. A helium ion would have an atomic number of 2. The atomic number does not change when an atom becomes an ion. This is because the atomic number is the number of protons in the nucleus, and an ion is formed when an atom gains or loses electrons, which are located in the electron cloud surrounding the nucleus. Gaseous chemical element, symbol: He, atomic number: 2 and atomic weight 4,0026 g/mol. Helium is one of the noble gases of group O in the periodic table. It’s the second lightest element. The main helium source in the world is a series of fields of natural gas in the United States.

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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:
• OSHAPermissible Exposure Limit (PEL)
  • No limits set by OSHA
• OSHA PEL Vacated 1989
  • No limits set by OSHA
• NIOSHRecommended 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.

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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
  Introduces stoichiometry and explains the differences between molarity, molality and normality.
• 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.

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Kenneth Barbalace. Periodic Table of Elements - Helium - He. EnvironmentalChemistry.com. 1995 - 2021. Accessed on-line: 4/24/2021
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