Why is ice less dense than liquid water at room temperature?

Question

answer in a non-scientist way

Answer 1

ignore the answers above
the crystalline structure of ice requires more volume for the same number of molecules because they must line up geometrically, thus it is less dense than liquid water and it floats
water expands when it freezes as it forms a solid phase

Answer 2

Ice does not exist at room temperature and pressure.

At zero degrees Celsius, the water molecules in ice are arranged in a crystalline structure which actually has the molecules farther apart than in liquid water. The molecules are farther apart, and therefore the solid takes up more volume, and is less dense.

Answer 3

The molecules of H2O in water are bouncing randomly around, which makes it a liquid. Usually molecules move closer together when a liquid becomes a solid, but because H2O molecules are strongly polarized, when they slow down and become a solid, they arrange themselves into a matrix that actually pushes them further apart--making ice less dense than water.

Answer 4

When water freezes the water molecules start to form an ordered structure. In a liquid they have no ordered structure so there are more molecules per unit of space. So a cubic inch of water has more more molecules in it...i.e. denser packing. A cubic inch of ice has fewer molecules because of the ordered structure....packed less densely.

Answer 5

Since ice assumes a crystal structure, there is a considerable amount of space in it's structure. When ice melts (forming liquid water), its structure collapses and more water molecules occupy a unit space as liquid than solid.

Answer 6

ice has air in it
air is less dense than water

so the air helps ice float


ta da

Answer 7

the molecules in ice are moving slower and there's more air.