2. Composition of Matter All matter is composed of Atoms Protons Found in the nucleus of atom positive (+) charge Mass Value  1 Neutrons found in nucleus of atom neutral (no) charge Mass value  1 Electrons found in clouds orbiting around nucleus negative (-) charge Mass value  0

3. Periodic Table of Elements Each element is made up of same atoms 1 H Hydrogen 1.0079 Atomic Number = Number of Protons (# P = # of electrons) Symbol – 1 st letter always CAPITAL 2 nd letter always lower cased Name Atomic Mass = Number of Protons + Number of Neutrons Number of Neutrons = Atomic Mass - Atomic Number Number of electrons must equal the number protons or the atom will be charged (+ or - ) = Ion

4. Atomic Models Most often represented as series of circles Center circle represents the nucleus - containing the protons (P+)and neutrons (N) Outer circles represent the electron clouds where electrons (e-) orbit

5. Bohr’s Model 6P 6N e- Each valence (orbit) has a specific number of electrons it can hold 1 st holds up to 2 e- 2 nd holds up to 8 e- 3 rd holds up to 8 e- 4 th holds up to 18 e- e- Carbon atom

6. Must remember that: Bohr’s Models are simple 2D models Atoms are actually 3D Electrons actually move around nucleus in an electron cloud not a linear orbit Atoms are active – drawings are stationary

7. Lewis Dot Model Uses dots to show Valance electrons – outermost orbit Valence Electrons are the ones that make the atom interactive Arranged in pairs on 4 sides of symbol – Shows “empty seats” N    

8. Why do Atoms React? They want to fill their “empty seats” on valence orbit Nitrogen has 3 “empty seats” Can add or lose electrons  IONic bond Can share electrons  Covalent N     X X X

9. Types of Bonds Ionic Bonds Atoms may gain or lose electrons to fill its valence shell This creates an imbalance of + and – creating a charged atom or ION Opposites attract Ex Na + Cl - Covalent Bonds Atoms may share electrons to fill valence shell ex. H 2 O Hydrogen Bonds Occur between H (only have 1 electron) weak bond Ex surface tension between H 2 O molecules

10. Why is Carbon so Important? Carbon has 6 protons; therefore has 6 electrons This leaves 4 empty seats for Carbon to fill Carbon will bond with LOTS of things BUT likes to bind with other C atoms. This creates the rings and chains of all the organic compounds

11. Molecules and Compounds M OLECULE – 2 definitions 1) 2 or more atoms of the same element joined together O 2 ; H 2 ; O 3 2) Smallest unit of a compound that has the properties of that compound C OMPOUND 2 or more different elements chemically combined H 2 O; CO 2 ; C 6 H 12 O 6

12. Polarity of Water Water (H 2 O) is made up of 2 H and 1 O sharing their electrons (covalent bond) There is a higher concentration of electrons on the Oxygen end making it slightly negative and the Hydrogen end slightly positive

13. Lipids are insoluble in water Because they are Not polar Have no ionic bonds Therefore, they are NOT attracted to water

14. pH The concentration of H+ in a solution measures the acidity or basicity of the solution H 2 O will break apart creating hydrogen ions (H+ ) and hydronium ions (OH-) More H+ = acid (< 7) More OH- = basic (alkaline) (>7) Equal amounts H+ & OH- = Neutral (pH7)

15. States of Matter: Matter on Earth can be found in three states: S OLIDS – molecules are barely moving; (ice cube) Little energy Definite volume Definite Shape

16. States of Matter L IQUIDS - molecules moving fairly freely (water)  More energy  Definite volume  No definite shape

17. States of Matter G ASES – molecules are moving rapidly (steam)  Lots of energy  No definite volume  No definite shape

18. Physical Change How do you know you saw a PHYSICAL CHANGE?

19. Change in: State, shape or size…

20. Change in STATE Solid Gas Liquid

21. Change in SIZE

22. Change in SHAPE

23. Chemical Change How can you tell there was a CHEMICAL REACTION!? Something NEW is formed…

24. New solid formed Precipitate

25. Unexpected color change Clear + Clear  PURPLE

26. Temperature change Increase (endothermic) or Decrease (exothermic)

27. New gas formed Bubbles Odor/smell Steam

28. Quiz – Identify as Chemical or Physical Change Slicing bread Physical Rust on nail Baking bread Melting Ice cream Chemical Physical