Helium-6 atom Please visit the Helium element page for information specific to the chemical element of the periodic table. Helium-6 decays by emitting a beta particle and has a half-life of 0.8 seconds. The most widely studied heavy helium isotope is helium-8. The most widely studied heavy helium isotope is helium-8. This isotope, as well as helium-6, are thought to consist of a normal helium-4 nucleus surrounded by a neutron 'halo' (containing two neutrons in 6. Helium has two known stable isotopes – 3 He and 4 He. The abundance of helium-3 and helium-4 corresponds to 0.0002% and 99.9998% respectively. This difference in abundances can be observed in the Earth’s atmosphere, where the ratio of 4 He atoms to 3 He atoms is approximately 1000000:1. Physical Properties of Helium.
Molar mass of He = 4.002602 g/mol
Convert grams Helium to moles or moles Helium to grams
| Symbol | # of Atoms | Helium | He | 4.002602 | 1 | 100.000% |
In chemistry, the formula weight is a quantity computed by multiplying the atomic weight (in atomic mass units) of each element in a chemical formula by the number of atoms of that element present in the formula, then adding all of these products together.
A common request on this site is to convert grams to moles. To complete this calculation, you have to know what substance you are trying to convert. The reason is that the molar mass of the substance affects the conversion. This site explains how to find molar mass.
Finding molar mass starts with units of grams per mole (g/mol). When calculating molecular weight of a chemical compound, it tells us how many grams are in one mole of that substance. The formula weight is simply the weight in atomic mass units of all the atoms in a given formula.
The atomic weights used on this site come from NIST, the National Institute of Standards and Technology. We use the most common isotopes. This is how to calculate molar mass (average molecular weight), which is based on isotropically weighted averages. This is not the same as molecular mass, which is the mass of a single molecule of well-defined isotopes. For bulk stoichiometric calculations, we are usually determining molar mass, which may also be called standard atomic weight or average atomic mass.
If the formula used in calculating molar mass is the molecular formula, the formula weight computed is the molecular weight. The percentage by weight of any atom or group of atoms in a compound can be computed by dividing the total weight of the atom (or group of atoms) in the formula by the formula weight and multiplying by 100.
Helium Isotope Notation
Using the chemical formula of the compound and the periodic table of elements, we can add up the atomic weights and calculate molecular weight of the substance.
Formula weights are especially useful in determining the relative weights of reagents and products in a chemical reaction. These relative weights computed from the chemical equation are sometimes called equation weights.
Chemical, Physical and Thermal Properties of Helium - He
Chemical, physical and thermal properties of Helium - He :
(values at 25oC (77oF, 298 K) and atmospheric pressure)
| Molecular Weight | 4.0026 |
| Specific Gravity, air = 1 | 0.138 |
| Specific Volume (ft3/lb, m3/kg) | 97.86, 6.11 |
| Density of liquid at atmospheric pressure (lb/ft3, kg/m3) | 7.80, 125 |
| Absolute Viscosity (lbm/ft s, centipoises) | 13.4 10-6, 0.02 |
| Sound velocity in gas (m/s) | 1015 |
| Specific Heat - cp - (Btu/lboF or cal/goC, J/kgK) | 1.24, 5188 |
| Specific Heat Ratio - cp/cv | 1.66 |
| Gas constant - R - (ft lb/lboR, J/kgoC) | 386, 2077 |
| Thermal Conductivity (Btu/hr ft oF, W/moC) | 0.086, 0.149 |
| Boiling Point - saturation pressure 14.7 psia and 760 mm Hg - (oF, oK) | -452, 4.22 |
| Latent Heat of Evaporation at boiling point (Btu/lb, J/kg) | 10.0, 23300 |
| Critical Temperature (oF, oK) | -450.3, 5.2 |
| Critical Pressure (psia, MN/m2) | 33.22, - |
| Critical Volume (ft3/lb, m3/kg) | 0.231, 0.0144 |
| Flammable | no |
Helium 600 Xxl
Follow the links below to get values for the listed properties of helium at varying pressure and temperature:
See also more about atmospheric pressure, and STP - Standard Temperature and Pressure & NTP - Normal Temperature and Pressure,
as well as Thermophysical properties of: Acetone, Acetylene, Air, Ammonia, Argon, Benzene, Butane, Carbon dioxide, Carbon monoxide, Ethane, Ethanol, Ethylene, Hydrogen, Hydrogen sulfide, Methane, Methanol, Nitrogen, Oxygen, Pentane, Propane, Toluene, Water and Heavy water, D2O.
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