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Water: Science Lesson: Activity 3 of 3



Water is a compound of two chemical elements: hydrogen and oxygen. A water molecule is made up of two hydrogen atoms bonded to an oxygen atom. The formula for water is H₂O.

Molecules are always in motion. The movement and distribution of the molecules are what determines the substance’s state of matter.

  • In the liquid state, water molecules move around freely, sliding and jostling against each other like dancers in a crowded room.
  • In solid ice, the water molecules slow down and are stacked in a crystal lattice pattern, like oranges packed neatly in a crate.
  • In the gas state, the water molecules are far apart and zoom around at the speed of flying bullets. The gas expands to fill whatever space is available.


Here are the diagrams that show the distribution of water molecules in the three different phases of matter.

Which diagram do you think represents water in its liquid state?

Question 1 of 10