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Particle model



Liquids and gases do not have a fixed shape. They can flow and fill their containers, but solids cannot. The particle model explains why.


Solids cannot flow because their particles are only able to vibrate and cannot move from place to place.


Liquids can flow because their particles can move over each other. When water is poured into a glass, the particles of water move over each other and into the corners of the glass. The particles keep on moving over each other as the water takes the shape of the glass. The animation shows how this works.

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Gases can flow because their particles can move in all directions. When a Bunsen burner is connected to a gas tap and turned on, natural gas flows through the rubber tubing. The particles of natural gas are free to move anywhere inside the tubing, and pressure forces them through the tubing into the Bunsen burner.


The particle model activity

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