What is Chemistry

1. What is Chemistry • Chemistry ‑ the study of matter and the changes matter undergoes. • Matter ‑ something that has mass and takes up space (has a volume).

2. States of Matter • Law of Conservation of Mass & Energy- • Matter can never be created nor destroyed; neither gained nor lost. It must be conserved.

3. Mass vs. Weight

4. Characteristics of Matter Chemical Properties • Ability for a substance to undergo a chemical change (new stuff) • Examples. • Ability to burn • Ability to rust • Ability to sour

5. Physical Properties Physical Properties observed or measured without altering makeup of substance (still the same stuff) • Examples • mass • weight • volume • color • solubility • luster • melting point • boiling point

6. Extensive depends on amount of matter present Examples mass weight volume Intensive: doesn't depend on amount present Examples color solubility luster melting point boiling point Intensive vs. Extensive Properties

7. Classification of Matter Separation

8. Classification of Matter Pure Substances • Elements- 118 on Periodic Table organized according to properties. • Named after famous scientists, countries, states, and planets • Abbreviation (Element symbols) begin with first letter capitalized. • Examples • Al - aluminum • O - oxygen • Hg - mercury (Latin hydrargyum) • Au - gold (Latin Aurum) • Cl - chlorine

9. Classification of Matter Compounds: element combined in a chemical rxn (reaction). • Can not be physically separated. • Many have both common names and scientific names. • Abbreviations (Chemical formulas) use element symbols • Examples • NaCl sodium chloride salt • NaOH sodium hydroxide Drano • NaHCO3 sodium bicarbonate Baking Soda • H2O Dihydrogen monoxide Water

10. Separation Separation by Physical Means • Filtration • Evaporation • Distillation • Chromatography Pure Substances Mixtures Separation

11. Classification of Matter Mixtures: can be physically separated • Methods of separation • Filtration – solid/liquid • Evaporation or crystallization – dissolved substance • Distillation – purifies a liquid or separates 2 liquids, based on different boiling points • Chromatography – separates a solution by allowing it to flow along a stationary substance (liquid, gas, paper).

12. Classification of Matter Types of Mixtures Homogeneous - the same composition throughout • Examples: • Pure air or Solutions (Kool-aid) • Alloys – Brass, Steel, Silverware Heterogeneous- varying composition throughout • Examples: • Chocolate Chip Cookies • River water

13. Types of Changes Substances can undergo three types of changes: • Physical • Chemical • Nuclear

14. Physical • Physical- though appearance (color, shape) may change, the mass will still be the same since the molecules remain the same • Examples: • Bending • Tearing • Melting

15. Separation Cont’d Compounds can only be separated chemically into elements Elements Compounds Separation

16. Chemical • Chemical- (Rxn) the structure of the substance changes. The new substance possesses different chemical and physical properties • Examples: • Burning • Molding • Souring

17. Parts of Chemical RXN 2 parts to a Chemical Rxn • Reactants  Products • Starting substances yields new substances with new properties. Three Indicators of Chemical Rxn’s • Formation of heat and/or light (energy) • Formation of a new gas (bubbles or fizzes) • Formation of a precipitate (solid formed for two solutions)

18. Nuclear • the structure of the nucleus changes. The energy involved is 6 to 8 times the Magnitude of a chemical or physical change.

19. Bunsen Burner Notes