Classifying Matter Notes

Mixtures

Matter is all mixed up! Matter is usually found in mixtures.

Mixture: 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.

Some properties of matter:
·  color
·  taste
·  melting point
·  boiling point
·  density / ·  luster
·  hardness
·  mass
·  volume
·  length
·  shape
·  reactivity

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. 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.

Two Types of Mixtures

1.  Homogenous mixtures (or solutions): the same throughout

2.  Heterogeneous mixtures: different parts that are not necessarily made up of exactly the same proportions.

Ex: A vegetable soup might give you different vegetables in every bite.

Heterogeneous VS Homogenous

There are two different substances One kind of substance in this mixture.
in this mixture.

Colloid: a mixture with larger particles that never settle. Ex: Fog, milk

Tyndall Effect: the scattering of light when shining through a colloid

Suspension: A heterogeneous mixture containing a liquid in which visible particles settle. Ex: dirty water

Substances

The parts of a mixture are called substances.

Substance: 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.

There is only one kind of substance in the container to the left.
You could group them by color, density, taste, melting point, boiling point, electrical conductivity, 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/properties that help you understand what you are studying.

Elements and Compounds

Most substances on Earth are in the form of compounds.

Compound: a substance made of two or more elements that CANNOT be separated by physical means. 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 were the basic building blocks of all matter.

Elements: contain only one kind of matter. Hydrogen is an example of an element.

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. You will learn how elements are organized.

ELEMENTS / COMPOUNDS / MIXTURES
Made up of only one kind of atom / Made up of more than one atom or kind of atom / Made up of more than one kind of molecule
Cannot be broken down / Can be broken down by chemical means / Can be separated by physical means
Has same properties as atoms making it up / Has different properties from elements making it up / Has same properties as substances making it up
Has same properties throughout / Has same properties throughout / Has different properties throughout
Set proportion of elements / Varying amounts of elements and compounds

Classification of Matter

Summary

·  Matter usually occurs in mixtures, which CAN be separated.

·  The parts of a mixture are substances and each substance has its own properties.

·  Most substances are combined in compounds and can be broken into their component substances using chemical means.

·  Some substances are called elements and CANNOT be broken down into other substances by chemical means.