How It Works

Why does water expand when it freezes?


The molecules of most elements are more compact in their solid form than they are in their liquid state, but water is different.

As you may know, each water molecule is made up of one oxygen atom with two hydrogen atoms attached. The hydrogen atoms in water have a positive charge and cause the water molecules to be attracted to one another. This attraction forces water to form a net of crystals with lots of gaps in it as it freezes.

The crystal net structure takes up more space than liquid water and so water expands as it turns to ice.

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  • Guest

    How does electric current work? The electrons move from one atom to another (of a metallic wire) but how does it works? Does it mean the previous atom is losing an electron? How many electrons from an atom move to the next? And what does it mean voltage? The electrons at the positive pole of a battery have more energy? Or less energy?