1. Pure Substances

2. What are ions??? IONS – Atoms with a charge! What determines how many electrons the ion has?

3. Forming Ions –Octet Rule (rule of 8’s) Elements with 5 or more valence electrons will take – GAIN electrons from others to get to 8 Which groups are these? Elements with 3 or less valence electrons will give up –LOSE electrons so they can be stable

4. Octet Rule (continued) Elements with 4 valence share their electrons. These elements form covalent compounds. Draw a line: ALMOST All Elements want to have a full electrons in valence shell….to be STABLE They will react with others to get there Exception: He and H only need 2 to feel happy

5. Octet Rule (continued) CATIONS – positively charged atoms, they have LOST electrons ANIONS – negatively charged atoms, they have GAINED electrons Let’s see how it happens…. http://www.youtube.com/watch?v=lODqdhx DtHMhttp://www.youtube.com/watch?v=lODqdhx DtHM

6. Forming Ions ElementValence e- Lose, gain, or share e- New Total electrons Charge of ion Calcium Silicon Bromine

7. Forming Ions ElementValence e- Lose, gain, or share e- New Total electrons Charge of ion Li O P

8. Forming Ions ElementValence e- Lose, gain, or share e- New Total electrons Charge of ion Ga Kr Ba

9. Compare/Contrast Ions and Isotopes

10. Pure Substances- COMPOUNDS What is a compound? 2 or more elements chemically bound together Ionic compounds (attraction between opposite charges) –Strong Bonds –Compounds have at least 1 metal Covalent compounds –Weak Bonds –Compounds made of nonmetals and/or metalloids only. NO METALS.

11. Ionic or Covalent? MgBr 2 SiO 4 CO 2 CoF H 2 O NaCl

12. Ionic or Covalent? Water?Alcohol?Melting point Conduct electricity? Sodium Chloride YNHighY SugarYNLowN Salicylic Acid NYLowN Sodium Carbonate YNHighY

13. Ionic Compounds Ionic compounds –Formed from the attraction between cations and anions. (Like a north and south pole of a magnet) –Water molecules can pull ionic compounds apart because the water molecule is polar. (Like a magnet) –Become electrolytes in H 2 O

14. Ionic Compounds

15. Dissolving Ionic Compounds Watch this demonstration

16. Ionic Compounds Why didn’t alcohol dissolve the ionic compounds? Once ionic compounds dissociate, electricity passes easily through the solution. Why? How are ions formed?

17. Naming Ionic Compounds The cation always comes first in the compound’s formula and name. –For binary compounds, the cation’s name is unchanged, but the anion’s name has “-ide” added to the end. Ex: Aluminum Fluoride, Barium Oxide –For compounds with polyatomic ions, the polyatomic’s name is unchanged, no matter what. All other rules apply. Ex: Calcium Nitrate, Ammonium Chloride

18. Writing Ionic Formulas The subscripts represent the number of ions needed to make a stable compound. (The compound should be neutral overall.) –Ex: Aluminum Fluoride Al 3+ and F - …..It takes 3 F - to match w/ one Al 3+ AlF 3 –Ex: Calcium Nitrate Ca 2+ and NO 3 -..It takes 2 NO 3 - to match w/ Ca 2+ Ca(NO 3 ) 2

19. Polyatomic Ions What does the prefix “poly” mean? What is an ion? Examples –Nitrate= NO 3 - –Phosphate = PO 4 3- –Ammonium = NH 4 + Don’t make any changes to the subscript of the polyatomic ion.

20. Covalent Compounds Covalent bonds are formed by atoms sharing their valence electrons. The shape of covalent compounds determines if they’re polar or non polar

21. Covalent Compounds Like dissolves like –Water dissolves polar covalent compounds (such as sugar) because water IS a polar covalent compound –What type of compound is alcohol? Which compound dissolved in alcohol? What type of compound was this substance? Covalent compounds don’t have charged atoms, so they don’t conduct electricity.

22. Covalent Compounds Octet Rule still applies! –Only exception is Hydrogen…it only needs 2 valence electrons to be stable. Lewis Dot diagrams for compounds –Hydrogen Bromide –Silicon Tetrafluoride –Nitrogen Trichloride

23. Potassium Nitrate 0 o C13.9g 20 o C31.6g 60 o C109g 100 o C245g

24. Potassium Chloride 0 o C28.0g 20 o C34.0g 60 o C45.8g 100 o C56.3g

25. Barium Hydroxide 0 o C1.67g 20 o C3.89g 60 o C20.94g 100 o C101.4g

26. Copper Sulfate 0 o C23.1g 20 o C32.0g 60 o C61.8g 100 o C114g

27. Warm Up 1.Parts of this mixture separate when allowed to sit for a while. 2.Jewelry and air are examples of this type of mixture. 3.This mixture acts like a solution, but light can be seen as it passes through.

28. When making Kool-Aid What’s the solute? What’s the solvent? What are three ways to get more of the SOLUTE to dissolve?

29. Ionic or Covalent? CO Ca 3 (PO 4 ) 2 Li 2 O CCl 4 AlBr 3

30. Warm Up For projectiles (on Earth) that have no initial vertical velocity, what is the only factor that affects how long it takes to hit the ground?

31. Warm Up Give the oxidation number (charge) for each of the following elements when they become ions. –Ex: Sodium = +1 Chlorine Aluminum Oxygen Phosphorus Strontium Francium