Changes in Matter

PHYSICAL PROPERTIES n Physical Properties - characteristics of a substance that can be observed without altering the identity of the substance. n Ex: length, mass, volume, density, color, melting point, etc.

Extensive vs. Intensive Properties n Extensive properties: dependent on the amount of substance present. –Ex: mass, volume, length n Intensive properties: independent of the amount of substance present. –Ex: density, color, melting point n Substances can be identified based on their intensive properties.

CHEMICAL PROPERTIES n Chemical Properties- characteristics of a substance that cannot be observed without altering the substance. n Ex: flammability (ability to burn in air)

n Physical Changes - a change that does not alter the chemical make-up of the substance. n Ex: changing from a pure substance to a mixture n Ex: Crushing, tearing, change in state

n Chemical Change - a change that alters the chemical make-up of a substance. n Ex: changing from an element to a compound n Ex: burning wood, cooking food.

n To identify a chemical change look for observable signs: color change bubbling and fizzing light production smoke presence of heat

P for physical change C for chemical change n 1. ____ A piece of wood burns to form ash. n 2. ____ Water evaporates into steam. n 3. ____ A piece of cork is cut in half. n 4. ____ A bicycle chain rusts. n 5. ____ Food is digested in the stomach. n 6. ____ Water is absorbed by a paper towel. n 7. ____ Hydrochloric Acid reacts with zinc. n 8. ____ A piece of an apple rots on the ground. n 9. ____ A tire is inflated with air.

P for physical change C for chemical change n 10. ____ A plant turns sunlight, CO 2, and water into sugar and oxygen. n 11. ____ Sugar dissolves in water. n 12. ____ You cut your hair. n 13. ____ Milk sours. n 14. ____ A popsicle melts. n 15. ____ Making a peanut, pretzel and cereal mixture. n 16. ____ Diamonds are used to scratch glass n 17. ____ Baking soda reacts with vinegar and forms a gas

P for physical change C for chemical change n 18. ____ A piece of metal is bent in half n 19. ____ Methanol is burned and leaves a residue n 20. ____ An aspirin is crushed into fine powder n 21. ____ Copper turns green when exposed to the environment n 22. ____ Two clear liquids are mixed and a yellow color forms n 23. ____ Baking cookies

Conservation of Matter n Law of Conservation of Matter: matter is neither created nor destroyed

Mixtures of Matter

Two Categories of Matter n 1. Pure Substances- Have their own set of chemical and physical properties. –Uniform and unchanging composition –Are any elements or compounds

Two Categories of Matter n 2. Mixtures- a blend of two or more pure substances. –Each substance keeps its own physical and chemical properties –Ex: seawater, milk, air

Types of Pure Substances 1. Element - a substance that cannot be separated into simpler substances by a chemical change. n Particle is the ATOM. n Ex: Hydrogen (H), Copper (Cu), Sodium (Na), Potassium (K)

Types of Pure Substances 2. Compound- formed when two or more different elements combine in a chemical reaction. n Most matter in the UNIVERSE is in the form of compounds n Particle is the MOLECULE n Ex: Water (H 2 O), Carbon Dioxide (CO 2 ), Table Salt (NaCl)

Types of Mixtures n 1. Homogeneous - mixture that is uniform throughout. –Another name for a homogeneous mixture is a solution. n Ex: pure air, soda, pancakes, Kool-Aid

Types of Mixtures n 2. Heterogeneous - mixture that is not uniform throughout. Does not blend smoothly n Ex: sand, chocolate chip cookies, tacos, fruit salad

Ways to separate mixtures….. n Filtration- separate a solid and a liquid. n Distillation- liquid from a liquid. n Crystallization- Solid particles from a dissolved solution. n Sublimation- two solids, when 1 sublimes and 1 does not. n Chromatography- gas and gas, or liquid and liquid n Or you can just pick things out.