1. Classifying Matter and the Changes Matter Undergoes

2.  Physical – a change in a substance that does NOT alter its fundamental properties (e.g. boiling point, melting point, color, chemical reactivity)

3. Examples of Physical Changes Phase change such as boiling or melting Formation of a solution Breaking or tearing

4.  Chemical – a change in a substance that does alter its fundamental properties (b.p., m.p. color, chemical reactivity)

5. Examples of Chemical Changes sodium + chlorine → sodium chloride Burning wood

6. Video links Link to breaking glass Reaction of sodium and chlorine Note: Color change and/or dramatic difference in appearance and/or large energy changes usually indicates chemical change.

7. Importance of Chemical vs Physical Processes in classifying compound vs mixture Substances that contain more than one type of atom are classified as either a compound (if the atoms can only be separated by a chemical reaction) or a mixture (if the atoms can only be separated by a physical process..

8. Homework 1-1 : Classify each change as chemical (C) or physical (P) p. 67 11,12,18abcdejk 11) Elemental mercury is a shiny, silver-colored, dense liquid that flows easily. Are these characteristics of mercury physical or chemical properties? 12) If liquid elemental mercury is heated in oxygen, the volume of the shiny liquid decreases and a reddish orange solids forms in its place. Do these characteristics represent a chemical change or a physical change?

9. Homework 1-1 18abcde 18a) A fireplace poker glows red when you heat it in the fire. 18b) A marshmallow gets black when toasted too long in a campfire. 18c) Hydrogen peroxide dental strips will make your teeth whiter. 18d) If you wash your jeans with chlorine bleach, they will fade. P C C C

10. Homework 1-1 18ejk 18e) If you spill some nail polish remover on your skin it will evaporate quickly. 18j) A log of wood is chopped up with an axe into smaller pieces of wood. 18k) A log of wood is burned in the fire place.

11.  ELEMENT – a substance composed of atoms of the same type  COMPOUND – a substance composed of two or more different types of elements CHEMICALLY BONDED together  MIXTURE – a substance composed of two or more different substances that can only be separated by PHYSICAL means

12. Classification of Matter Atom – smallest chemical building block Molecule – 2 or more atoms bonded together Homogeneous – uniform throughout Heterogeneous – different – nonuniform throughout

13. Atomic Level Representations of Elements, Compounds and Mixtures

14. ELEMENT – substance composed of 1 type of atom Cannot be broken down into simpler substance by either chemical or physical process Element symbols are listed on periodic table

15. Examples of Elements Hydrogen (H): Oxygen (O): Copper (Cu): Iron (Fe):

16. Elements may be either monoatomic or diatomic Monoatomic – exist as individual atoms Diatomic elements – exist in pairs of identical atoms bonded (7 diatomic elements: H 2, N 2, O 2, F 2, Cl 2, Br 2, I 2 ) Br is diatomic; Ar is monoatomic

17. 7 diatomic elements – memorize for test H2H2 N2N2 O2O2 F2F2 Cl 2 Br 2 I2I2

18. Compounds can only be separated into the elements that make up the substance by a CHEMICAL REACTION.

19. Examples of Compounds Water: H 2 O Salt: NaCl Sugar: C 6 H 12 O 6

20. MIXTURE MIXTURE – Composed of two or more substances which can only be separated by a PHYSICAL PROCESS Most of the substances we see around us are mixtures Examples of mixtures Salt water Oil and water Apple

21. Mixtures can be combinations of elements or compounds Mixture of elements: Mixture of elements and compounds Mixture of compounds:

23. Which of the following are elements and which are compounds? How many atoms are present? How many molecules are present?