What term is used to describe the heaviness of a gas compared to air?

The term that describes the heaviness of a gas compared to air is density. Density is defined as the mass of a substance divided by its volume, which directly relates to how heavy or light a gas is in comparison to air. When considering gases, a higher density indicates that the gas is heavier than air, while a lower density suggests that it is lighter.

For example, when evaluating gases in different environments, understanding their densities helps predict how they will behave when released; gases with densities less than that of air will rise, while those with greater density will tend to settle.

In contrast, volume refers to the amount of space that a substance occupies, weight pertains to the force exerted by gravity on that substance, and pressure measures the force exerted per unit area. While these concepts relate to gases and their behavior, none directly defines the comparative heaviness of a gas as density does.