Earth Science SOL Practice Test 2026 – Your All-in-One Guide to Mastering the Standards!

Density is mass per unit volume, and for water the arrangement of molecules changes with the phase. In the liquid form, water molecules are packed closely together, giving a density around 1 g per cubic centimeter (with the maximum density of liquid water near 4°C). Ice, on the other hand, forms an open hexagonal lattice due to hydrogen bonding, which makes it less dense and causes it to float on liquid water. Water vapor is a gas with molecules far apart, so its density is much lower than that of liquid water. So, among the common forms, the liquid state is the most dense.