Air, Water and Other Things

Everything in this world takes up space and has weight – even air.

The three states of matter are solid, liquid, and gas. This refers to how a thing feels, how hard it is, or how it moves or looks, even if it’s invisible, like air. A table is a solid object, water is a liquid, and air is a gas. These three things are made up of small parts called molecules and even smaller parts called atoms. These small parts are that chemists study and rearrange to create new products that make our lives much better.

Atomie Brew: The Molecule and I
A molecule is the smallest part of anything. You cannot see molecules, but everything in the world is made up of them. The best way to understand this is to imagine yourself shrinking way, way down until you become a molecule. If you were a wood molecule on a tabletop, a salt crystal (one grain of salt) on the table would look like a mountain to you. If you were a molecule of water, you would be the littlest part of a drop. The last part of that water drop to evaporate would be you. But, while molecules are small, the parts that make them up are even smaller. These very small parts that form molecules are called atoms.

If you were a molecule of oxygen, you would be made up of two atoms. You would need two atoms of oxygen, because one atom of oxygen does not behave like oxygen.

A substance with only one kind of atom is called an element. Oxygen, hydrogen, nitrogen, and carbon are all elements. If you were an element of nitrogen, you would be made up of only nitrogen atoms. If you were an element of carbon, you would be made up of only carbon atoms. You could not be anything else.

Atoms of different elements come together to make different molecules. A molecule of water is made up of three atoms. If you were one atom of oxygen, you would have to be joined by two friends representing hydrogen atoms to make a molecule of water, because water has two atoms of hydrogen and one atom of oxygen. You would now be a substance, made up of two (or more) different elements, called a compound. Water, carbon dioxide, and sugar are all examples of compounds. As a molecule you could exit in three possible forms. Chemists would identify you as one of the three states of matter: solid, liquid, or gas.

If necessary, a scientist, or chemist, could again split you apart, using electricity, back into your original parts. Now you would no longer be water but three separate atoms – two hydrogen atoms and one oxygen atom. The very smallest part of you that could ever exist as water would have to be a molecule.

Before you begin chemistry experiments

• Before you begin doing some experiments in chemistry, be smart and do them safely by following these rules:
• Always wash thoroughly any kitchen containers, bowls, or tools you use before you put them back.
• Don’t leave old chemical solutions lying around the house. Dispose of them safely.
• Get an adult to help you perform the experiment. We reiterate, experiments should not be performed without the help of an adult.
• Be sure to label the contents of any bottles, jars, and containers you want to keep, and store them in a safe place, away from young children.
• Make sure you have everything you need and the time to complete the experiment.
• If an experiment may be messy, do it outside or in the sink, or cover your work area with a protective covering such as old newspapers.