Chapter 12 page 299
The molecules of water are always moving. The molecules in the water are moving all
around, and they never stop moving. They are always sliding past and bumping into each
other.
Except for when they bump against each other, the water molecules do not touch each
other. There is nothing at all between the water molecules, just empty space. There is no air.
There is no water. There is just absolutely nothing. It might seem strange to you that there
could be lots of empty space in water. But of course, we can’t see the spaces because they
are so very very small.
You know that water stays together. A drop of water doesn’t suddenly, all by itself, fly
apart and break into lots of littler drops. Water, like other liquids, stays together because there
are weak electrical attractions between the molecules. The weak attraction is like an extremely
weak magnet, much weaker than the magnets we use every day. As the water molecules
constantly move around, they form temporary electrical attractions to each other. Each
molecule makes and breaks many different electrical attractions every second as it moves
around. The molecules are like very very weak magnets that keep moving around all the time.
So scientists are saying that every liquid you’ve ever seen is made of molecules--water,
soda pop, lemonade, melted butter, rubbing alcohol, melted steel, motor oil, cooking oil, and so
on. All of these liquids are made of little tiny molecules moving all around with empty space
between them. It may seem strange, because water doesn’t LOOK like it’s made of tiny
molecules moving all around. Neither does cooking oil or any other liquid. But scientists think
that even though we can’t see the molecules, all liquids are made of molecules moving all
around with empty space between them.
Why can you pour water? The answer is that the water molecules have only weak
attraction for each other. Since the attraction is very weak, they can always moving around all
around each other and all over the place. So when you pour water, the water molecules just
slide past each other in the same direction that you’re pouring.