1. Composition of Matter CHAPTER 15 SECTION 1 HTTPS://WWW.BRAINPOP.COM/SCIENCE/MATTERANDCHEMISTRY/COMPOUNDSAN DMIXTURES/

2. Pure Substances  A type of matter with a fixed composition or, in other words, a fixed combination  A substance can either be an element or a compound

3. Elements  A substance with atoms that are all alike  All substances are built from atoms  Graphite in your pencil point or the copper coating of most pennies

4. Compounds  A substance in which the atoms of two or more elements are combined in a fixed proportion  Examples  Water is a compound- two atoms of hydrogen combine with one atom of oxygen  Chalk is a compound- contains one calcium atom, one carbon atom, and three oxygen atoms  Salt is a compound- made of sodium, which is a silvery metal, and chlorine, a poisonous gas.

5. Mixtures  A material made up of two or more substances that can be easily separated by physical means  Pizza and soft drinks are mixtures  There are three different types of mixtures. Those are...

6. Heterogeneous Mixtures  A mixture in which different materials can be distinguished easily  A pizza is a heterogeneous mixture because you can easily see that there is cheese, pepperoni, and crust which are all different.  Mixtures do not always contain the same proportions of the substances that make them up  Some clothing items that are made of cotton and polyester are heterogeneous mixtures  Even though you can not see the two different fabrics with the naked eye, you can see them with a microscope  Some heterogeneous mixtures have heterogeneous mixtures within them  The cheese in the pizza is a heterogeneous mixture.

7. Homogeneous Mixtures  Contains two or more gaseous, liquid, or solid substances that are blended evenly throughout  A soft drink is a homogeneous mixture but when the carbon dioxide fizzes, the soft drink becomes a heterogeneous mixture  Vinegar is a homogeneous mixture but is also be a solution  A solution is a homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle to the bottom of their container

8. Colloids  A type of mixture with particles that are larger than those in solutions but not heavy enough to settle to the bottom of their container  Examples of colloids  Paint- a liquid with suspended colloid particles  Fog- consists of particles of liquid water that are suspended in air  Smoke- contains solids suspended in air  Fun Fact: The word Colloid comes from the Greek word for glue and the first colloids were found in gelatin which was used in some glues

9. Detecting Colloids  Appearance is one way to distinguish a colloid from a substance  You can tell for certain if a liquid is a colloid by passing a beam of light through it.  If the light is invisible= a solution  If the light is seen readily= a colloid  Light can be seen passing through a colloid because the particles in the colloid are large enough to scatter light. Those in a solution are not.  This scattering of light by particles within the colloid is called the Tyndall Effect  Examples of Colloids  Fog appears white because its particles are large enough to scatter light  Some shampoos and gelatins are colloids called gels that appear almost clear

10. Suspensions  A heterogeneous mixture containing a liquid in which visible particles settle  An example of a suspension would be muddy pond water  If the pond water stands long enough, some mud particles will fall to the bottom and the water will clear

11. Review  A Pure Substance is a type of matter with a fixed composition  A Substance can be an element or a compound  An Element is a substance with atoms that are alike  A Compound is a substance with atoms of two or more elements are combined in a specific combination  A Mixture is a material made up of two or more substances and can be easily separated  A Heterogeneous Mixture is a mixture in which different materials can be distinguished easily  A Homogeneous Mixture contains two or more gaseous, liquid, or solid substances that are evenly blended  A Solution is a Homogeneous Mixture of particles that cannot even be seen through a Microscope  Colloids are a type of mixture and have particles bigger than those in solutions  A Suspension is a heterogeneous Mixture containing a liquid in which the particle that you can see can settle