What is the density?
Density is a measure of how compact the mass in a substance or object is. The density of an object or substance can be calculated from this equation: density in kilograms per meter cubed is equal to the mass in kilograms, divided by volume in meters cubed. Density is a measure of mass per unit of volume. In general, gases have the lowest densities, but these densities are highly dependent on the pressure and temperature which must always be specified. The density range of solids is quite wide. Metals, whose atoms pack together quite compactly, have the highest densities, although that of lithium, the highest metallic element, is quite low.