1. Matter & Properties of Matter 8 th Grade Science

2. What is Matter?  Anything that has mass & takes up space

3. Matter is either…  Substance  Single kind of matter, fixed composition  Examples: Table salt, sugar, baking soda,  or Not Substance  More than a single kind of matter, composition can change  Examples: muffin mix (made up of substance), flour, milk, eggs, fruit

4. Substance or Not Substance…?

5. Properties of Matter  Physical properties are characteristics that can be observed without changing the matter into another substance  Chemical properties are characteristics that describe the ability to change into another substance

6. Examples of Each  Physical Properties  Water freezing to ice at 32°F  Whether or not a substance dissolves in water  Texture  Color  Chemical Properties  Chemicals that are combustible vs. ones that are not  rusting

7. Elements  Pure substance that cannot be broken down into any other substances  Everything is made up of a little more than 100 elements  Simplest substances

8. Particles of Elements  Atoms are the particles of elements  Atoms are made of even smaller particles:  A nucleus which is positively charged and it is surrounded by a cloud of electrons (which have a negative charge).

9. Atoms

10. Chemical bonds  When atoms combine they form chemical bonds which is a force of attraction between two or more atoms.  In many cases, atoms combine to form larger particles called molecules.  Molecules are groups of two or more atoms held together by chemical bonds.  Examples: water, oxygen, and carbon dioxide. Water Molecule (H 2 O) Oxygen Molecule (O 2 )

11. Compounds  Compounds are pure substances made of two or more elements chemically combined into a fixed ratio.  A compound may be represented by a chemical abbreviation.  When two or more elements are placed together the result is a compound which has different characteristics than either of the original elements. Calcium Carbonate (Compound) (Shell of a snail) Calcium (element) Carbon (element) Oxygen (element) CaCO 3

12.  Made of two or more substances (elements, compounds, or both)  They are NOT chemically combined  Can be separated physically  Each substance in a mixture keeps its individual properties  Give some examples of mixtures  Salt water, soil, bag of marbles What is a Mixture?

13. Heterogeneous Mixtures  A heterogeneous mixture is when two or more substances are mixed but do not combine chemically to form a single substance.  Examples: salad, oil and water, rocks, chocolate chip cookie, chicken soup, etc.  We can separate all the components of the salad to the left, so it is a heterogeneous mixture.

14. Homogenous Mixture  A homogeneous mixture is what you have when you mix two or more substances together so that the composition is the same throughout the mixture.  Examples: sugar and water, brass (mixture of copper and zinc), air that we breathe (oxygen and nitrogen gases), soft drinks, milk, etc.  A solution is an example of an homogeneous mixture.

15. The two types of changes in matter Physical changes: any change that alters the form or appearance of the matter, but does not alter the properties of the matter. A substance that undergoes a physical change is still the same substance after the change. Example: water exists as a solid, liquid, or a gas. Chemical changes: any change which results in the production of one or more new substances is a chemical change. The properties of the new substances are different than the properties of the original substances. Example: Hydrogen peroxide turns into water and oxygen gas when it is used.

16. Law of the conservation of matter  Simply stated that when matter changes either chemically or physically, that matter is not created nor destroyed, it has just changed to another form or forms.  Example: CH4 (methane) + 2O2 (oxygen) = CO2 (carbon dioxide) + 2H2O (water) Notice how the number of atoms did not change after the combustion.

17. Matter is neither created nor destroyed: Before the reaction CH 4 (methane) + 2O 2 (oxygen) The total number of atoms before the reaction is: 1 Carbon (C) 4 Hydrogen (H) 4 Oxygen (O) After the reaction CO 2 (carbon dioxide) + 2H 2 O (water) The total number of atoms after the reaction is: 1 Carbon (C) 4 Hydrogen (H) 4 Oxygen (O)