1 Classifying Matter Pure Substance or Mixture?

2 What is Matter? Matter is anything that has mass, and takes up space. 1. Matter is anything that has mass, and takes up space. measure of the amount of “stuff” (or material) the object contains. 2. Mass is a measure of the amount of “stuff” (or material) the object contains. (don’t confuse this with weight-- a measure of gravity’s effect on mass) Volumeis a measure of the space occupied by the object 3. Volume is a measure of the space occupied by the object

3 What is a Pure Substance? 4. A Pure Substance is matter that has a definite composition. (There is only one type of stuff and it is exactly the same everywhere). 5. There are two types of substances: Substances Compounds (Two or more elements chemically bonded together. ) Elements

4 What is an Element? 6. An element-- a. is the simplest kind of matter. Cannot be broken down any simpler and still have properties of that element. b. Cannot be broken down any simpler and still have properties of that element. c. is all one kind of atom. d. Examples – From the periodic table: Helium (He), Iron (Fe), Oxygen (O 2 )

5 What is a Compound? 7. A compound is: a. a substance that is made from the atoms of 2 or more different elements that are chemically bonded. b. They can be broken down only by chemical methods c. when broken down, the pieces have completely different properties than the original compound. e. Example – Water, H 2 O  H 2 + O 2 (Compound)  (elements) (Compound)  (elements)

6 Silver and bromine chemically combine to form silver bromide 8. A compound has different properties than the elements that make it up have by themselves. Element Silver Element Bromine Compound Silver Bromide + Ag Br 2 AgBr

7 1.Identify the elements? 2.Identify the compounds? 3. Identify the substances? Sodium + Na + Chlorine gas Cl 2 Sodium Chloride NaCl

8 What is a Mixture? 9. A mixture is: a. A physical blend of two or more different substances. (no new chemical is being formed) 10. The basic identity of each substance is not changed when mixtures are formed.

9 11. There are two types of mixtures: Mixtures HeterogeneousHomogenous

10 Heterogeneous means the mixture is not uniform in composition. 14. Heterogeneous means the mixture is not uniform in composition. a. Differences between substances can clearly be seen with the naked eye b. Examples: Chocolate chip cookie, oil and water, sand and water.

11 Homogeneous mixtures are mixtures that have a uniform composition. 15. Homogeneous mixtures are mixtures that have a uniform composition. a. Different substances cannot be seen with the naked eye. b. Every part keeps its own properties. c. Homogenous mixtures are also called solutions. d. Examples: Kool-aid, air, salt water

12 Classification of Matter

13 Quick Review 1. What’s the difference between elements and compounds? 2. What’s the difference between substances and mixtures? 3. What’s the difference between mixtures and compounds?

14 Compound vs. Mixture CompoundMixture Made of one kind of material Made of more than one kind of material Made by a chemical change Made by a physical change Definite composition Variable composition

15 Classification of Matter

What is the difference between a physical change and a chemical change?

17 Physical change will change the visible appearance, without changing the chemical composition of the material. 17. A Physical change will change the visible appearance, without changing the chemical composition of the material. a. Examples: Boil, melt, freeze, cut, bend, split, crack, dissolving, crystallizing b. Any phase change is a physical change! (Is boiled water still water?) 18. Physical changes are usually reversible

18 Solid Liquid Gas Melt Evaporate Condense Freeze Physical Changes!!!!

A Chemical change occurs when one or more substances are converted into different substances. (a new chemical forms) 20. This is also known as a chemical reaction. 21. A new form of matter with different properties is formed. a. Examples - Rusting, burning, decompose…

Recognizing Chemical Reactions: 1)Energy is absorbed or released (temperature or colder) 1)Energy is absorbed or released (temperature changes--hotter or colder) 2)Color changes that are unexpected. 3)Gas production (bubbling, fizzing, or odor change; smoke) 4)formation of a precipitate - a solid that separates from solution (won’t dissolve) 5)Irreversibility - not easily reversed There are examples of these that are not chemical changes– boiling water & bubbles, etc.