2. Chemical Symbols of Common Elements Prepare a chart in your notes …

3. Complete for elements:1-20, 26, 28- 30, 35, 47, 50, 53, 79, 80, 82, 92 Use the chart on left to complete the two last columns (only listed elements will have anything for these columns). ZNameSymbol*Latin*Mnemonic 1HydrogenH 2HeliumHe ElementLatin name CopperCuprum GoldAurum IronFerrum LeadPlumbum MercuryHydrargyrum PotassiumKalium SilverArgentum SodiumNatrium TinStannum

4. Mnemonics Mnemonics are ways to help you remember Used by A students and experts They are often rhymes or visual connections E.g. “Thirty days has September, April, June and November, all the rest have 31” Iron (Fe) … Iron  strong  opposite is feeble  Fe A bad mnemonic for Cu is a copper cup (any metal can be made into a cup) A good mnemonic for Cu is a cup full of pennies It may seem like more to know, but it works

5. Mnemonics from Chembored Sodium (Na) Salt?  Bad for Blood Pressure  (Na, don’t want it) Potassium (K) Kangaroo eating bananas (have potassium)

6. Mnemonics Iron (Fe) Iron = strong giant = Fe-Fi-Fo-Fum Copper (Cu) A Cup filled with pennies

7. Mnemonics Mercury (Hg) thermometer goes down = Hug to stay warm Hot gas Lead (Pb) Plumber used lead pipes (not anymore) For more lessons, visit www.chalkbored.com www.chalkbored.com

8. Mnemonics Silver (Ag) Almost gold Aging = grey hair = silver Tin (Sn) “Tin is Sin” Gold (Au) Always united (wedding ring) Gold = shiny = aura

9. Quiz yourself on Elements 1-12, sodium, potassium, iron, copper, mercury, lead, silver, tin, gold 1 Hydrogen 2 Helium 3 Lithium 4 Beryllium 5 Boron 6 Carbon 7 Nitrogen 8 Oxygen

10. Quiz Yourself 9. Fluorine 10. Neon 11. Sodium 12. Magnesium 26. Iron 29. Copper 80. Mercury 82. Lead

11. Quiz Yourself 47. Silver 50. Tin 79. Gold

12. Periodic Table Periodic Table Rap

13. Electronegativity ++ –– 00 00 HClHH

14. The basic units: ionic vs. covalent Ionic compounds form repeating units. Covalent compounds form distinct molecules. Consider adding to NaCl(s) vs. H 2 O(s): H O H Cl Na Cl Na H O H H O H NaCl: atoms of Cl and Na can add individually forming a compound with million of atoms. H 2 O: O and H cannot add individually, instead molecules of H 2 O form the basic unit.

15. Holding it together Q:Consider a glass of water. Why do molecules of water stay together? A:there must be attractive forces. Intramolecular forces occur between atoms Intermolecular forces occur between molecules We do not consider intermolecular forces in ionic bonding because there are no molecules. We will see that the type of intramolecular bond determines the type of intermolecular force. Intramolecular forces are much stronger

16. I’m not stealing, I’m sharing unequally We described ionic bonds as stealing electrons In fact, all bonds share – equally or unequally. Note how bonding electrons spend their time: Point: the bonding electrons are shared in each compound, but are not always shared equally. The greek symbol  indicates “partial charge”. H2H2 HClLiCl ++ –– 00 00 +– covalent (non-polar) polar covalent ionic HH H Cl [Li] + [ Cl ] –

17. Electronegativity Recall that electronegativity is “a number that describes the relative ability of an atom, when bonded, to attract electrons”. The periodic table has electronegativity values. We can determine the nature of a bond based on  EN (electronegativity difference).  EN = higher EN – lower EN NBr 3 :  EN = 3.0 – 2.8 = 0.2 (for all 3 bonds). Basically: a  EN below 0.5 = covalent, 0.5 - 1.7 = polar covalent, above 1.7 = ionic Determine the  EN and bond type for these: HCl, CrO, Br 2, H 2 O, CH 4, KCl

18. Electronegativity Answers HCl:3.0 – 2.1 = 0.9 polar covalent CrO:3.5 – 1.6 =1.9ionic Br 2 :2.8 – 2.8 =0covalent H 2 O:3.5 – 2.1 =1.4polar covalent CH 4 :2.5 – 2.1 =0.4covalent KCl:3.0 – 0.8 =2.2ionic

19. Electronegativity & physical properties Electronegativity can help to explain properties of compounds like those in the lab. ++ –– ++ –– ++ –– ++ –– Lets look at HCl: partial charges keep molecules together. The situation is similar in NaCl, but the attraction is even greater (  EN = 2.1 vs. 0.9 for HCl). Which would have a higher melting/boiling point? NaCl because of its greater  EN. For each, pick the one with the lower boiling point a) CaCl 2, CaF 2 b) KCl, LiBr c) H 2 O, H 2 S – + + – CaCl 2 would have a lower melting/boiling point: CaCl 2 = 3.0 – 1.0 = 2.0 CaF 2 = 4.0 – 1.0 = 3.0 LiBr would have a lower melting/boiling point: KCl = 3.0 – 0.8 = 2.2 LiBr = 2.8 – 1.0 = 1.8 H 2 S would have a lower melting/boiling point: H 2 O= 3.5 – 2.1 = 1.4 H 2 S = 2.5 – 2.1 = 0.4 Note: other factors such as atomic size within molecules also affects melting and boiling points.  EN is an important factor but not the only factor. It is most useful when comparing atoms and molecules of similar size.

20. CaCl 2 would have a lower melting/boiling point: CaCl 2 = 3.0 – 1.0 = 2.0 CaF 2 = 4.0 – 1.0 = 3.0 LiBr would have a lower melting/boiling point: KCl = 3.0 – 0.8 = 2.2 LiBr = 2.8 – 1.0 = 1.8 H 2 S would have a lower melting/boiling point: H 2 O= 3.5 – 2.1 = 1.4 H 2 S = 2.5 – 2.1 = 0.4 Note: other factors such as atomic size within molecules also affects melting and boiling points.  EN is an important factor but not the only factor. It is most useful when comparing atoms and molecules of similar size.

21. Why oil and water don’t mix Lets take a look at why oil and water don’t mix (oil is non-polar, water is polar) ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ ++ –– ++ The partial charges on water attract, pushing the oil (with no partial charge) out of the way.