The third thing we have to do is to classify matter, or sort it into groups. This is not easy. Normally, matter is all mixed up! That is, matter is usually found in mixtures. A mixture is a combination of different kinds of matter, in which the different kinds are not changed by being put together. The parts of a mixture can be separated. They can be separated by using the properties of the substances.
For example, if you mix jellybeans and pebbles together, the pebbles stay pebbles and the jellybeans stay jellybeans. If you were patient, you could pick out the jellybeans one by one and eat them (without breaking your teeth). You probably used the property of color to find the parts of the mixture.
But a jellybean is a mixture too, a mixture of coloring, sugar, and flavoring. Could you pick out the parts of a jellybean just using your fingers? Probably not. Some mixtures are harder to sort out than others, like jellybeans or salt water. Chemists are very good at figuring out ways to separate mixtures, because they know the properties of many different kinds of matter.
There are two different substances in this mixture
The parts of a mixture are called substances. A substance (SUB-stans) is made of only one kind of matter. Each substance has its own properties which do not change. This is how chemists can tell one substance apart from another, and why knowing the properties of matter is important. A chemist is a kind of detective in some ways.
There is only one kind of substance in this container
There are different ways of sorting substances into groups. You could group them by color, or by hardness, or by whether they are poisonous. You could group them by state: solid, liquid, or gas. However, whatever groups you choose, they should be useful groups that help you understand what you are studying.
Most substances on Earth are in the form of compounds. A compound (COM-pownd) is a substance which has its own properties but which can be broken down into other substances. Chemists break down compounds using special chemical methods which may include heat, electricity, and adding other substances to the compounds.
Even in the time of the alchemists, people knew that there were some kinds of substances which were special because they could not be broken down. These substances, called elements (ELL-uh-mentz), were the basic building blocks of all matter. All other matter could be broken down into elements, but elements could not be broken into anything else. These substances, such as silver, lead, mercury, tin, copper, gold, and iron, were known to the alchemists. Gradually, more elements were discovered, and today there are 110 known elements.
To see if a substance is a compound, chemists often cause a chemical reaction. If a reaction happens and the substance separates into two or more different substances, it was a compound. If no reaction happens, the substance is an element.
Sorting matter into these groups turned out to be very important and helpful for learning how matter is put together. In later sections of this unit, you will learn how elements are organized.
Classification of Matter