The shape of a liquid can change because of the bonds between its atoms. Atoms in a liquid are loosely bonded, allowing them to roll over one another but not completely escape one another. In contrast, the atoms in a solid are so closely packed together that they can only vibrate in place, while the atoms in a gas have such little attraction between them that they fly in every direction and do not stay near one another at all. In a liquid, the atoms still stay close to one another, but are able to move, changing the overall shape of the liquid.
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