Physical Properties
Helium is a colorless, odorless, tasteless gas. It has a number of unusual properties.
For example, it has the lowest boiling point of any element. Helium is the only gas that cannot be made into a solid simply by lowering the temperature. It is also necessary to increase the pressure on the gas in order to make it a solid. At a temperature of about -271°C (-456°F), helium undergoes an unusual change. It remains a liquid, but a liquid with strange properties. Superfluidity is one of these properties. The forms of helium are so different that they are given different names. Above -271°C, liquid helium is called helium I; below that temperature, it is called helium II.
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