Monatomic gas exists as a single atom and does not bound to each other. They are stable at standard room temperature. There is no chemical bond involved in these gases. They are very unreactive due to the completely full outer valence shell.

1 Introduction. The molar specific heat capacity of a gas at constant volume Cv is the amount of heat required to raise the temperature of 1 mol of the gas by 1◦C at the constant volume. Its value for monatomic ideal gas is 3R/2 and the value for diatomic ideal gas is 5R/2.

Monatomic is a combination of two words “mono” and “atomic” means a single atom. The noble gases are monatomic gases as they are unreactive in nature which is a property of these gases. They do find applications in daily life like: Helium is used in filling balloons as their density is lower than that of the air.

noble gases

Thermodynamic properties Also, for ideal monatomic gases: the molar heat capacity at constant pressure (Cp) is 5/2 R = 20.8 J K−1 mol−1 (4.97 cal K−1 mol−1). the molar heat capacity at constant volume (Cv) is 3/2 R = 12.5 J K−1 mol−1 (2.98 cal K−1 mol−1).

Thus, freezing point is an intensive property and doesn’t change when we vary amount. Other examples of intensive properties are color, boiling point, pressure, molecular weight and density. Density is an interesting example. Remember that density is mass divided by volume.

Temperature remains intensive through- out the system. This occurs even though surface properties, like surface area and luminosity, are not extensive, while bulk properties, like mass and volume, are extensive.

Mass and volume are examples of extensive properties. An intensive property is a property of matter that depends only on the type of matter in a sample and not on the amount. Color, temperature, and solubility are examples of intensive properties.