Why is liquid water more dense than ice?
Pure liquid water reaches its greatest density (the quantity of something per unit measure) at 39.2° Fahrenheit (3.98° Celsius) and decreases in density as it freezes. The water molecules (particles made by the combination of two or more atoms) in ice are held in a rigid, six-sided geometric pattern by their hydrogen bonds. This produces an open, porous structure. The molecules in liquid water are more loosely bonded. A greater number of liquid water molecules than ice molecules can occupy a given volume (amount). Therefore, liquid water is more dense than ice. Source: Leopold, Luna B. Water, p. 30.
