1. ATOMIC BOOKKEEPING. 12 0 31150 17O910 Atomic # mass# symbol #p + #n o #e - atom charge 12 2412Mg 15 16P 88-2 Pertinent section of Periodic table

2. 20100 714 Fe300 171819 10 26 56 35 Ne N Cl 10 Atomic # mass# symbol #p + #n o #e - atom charge 7 26 17 10 7 8 26 -2 Let’s go down a column left to right….

3. 6 C 12.01 12 O C 6 Periodic table entry for `average’ atom of C Nuclear notation for specific isotope of C Average atomic mass (not mass number ??) Atomic # = p Mass #= n + p Atomic # = p charge The Chemist’s element vs. the Physicist’s element Chemist’s elementPhysicist’s element

4. Why the chemist’s C lists 12.01 and not 12 # p # n mass # caught out of 100 C atoms 66 99 Imagine `fishing’ out 100 atoms of Carbon from a sample of graphite (pure carbon). What would you catch ? 12 6 713 1 Both kinds isotopes of C act exactly the same, chemically so chemists just average the masses Average mass = of C 99*12 + 1*13 100 = 12.01

5. Average mass = of each C 99*12 + 1*13 100 = 12.01 = 99 *12 + 1 * 13 100 100 Averages Written As Sums Of Fractional Contributions =f 12 *12 + f 13 *13 f m = fraction of C atoms with mass M

6. Averages written as sums of % contributions = 99 *12 + 1 * 13 100 100 Average mass of each C =(99 % *12 + 1% * 13) 100 = (P 12 *12 + P 13 *13) 100 P m = % of C atoms with mass M

7. Take home lesson AV. MASS =f 1 *m 1 +f 2 *m 2 +….. Or, from % abundances P k and m k so: AV. MASS =P 1 *m 1 +P 2 *m 2 +….. 100 : Average mass is computable from fractional abundances f k and m k so:

8. In- class exercise with mercury: Compute the average mass of Hg from abundance data 1881 3144 5720 2492 5555 1246 Sum= 20057

9.  Average mass of Hg =20057 =200.57 100 AV. MASS =P 1 *m 1 +P 2 *m 2 +….. 100

10. COMPOUND NAMING REVIEW (pp. 60-69) (type 1) metals, M Non metals (NM) (type 2), transition metals,TM NM

11. REVIEW OF BINARY NAMING CLASSES NM + NM M + NM TM + NM Example FORMULA NAME N 2 Cl 4 dinitrogen tetrachloride Mg 3 P 2 magnesium phosphide TiCl 4 titanium (IV) chloride Naming classes NM= non-metals in `blue’

12. Name Na 2 O A.disodium monoxide B.sodium (I) oxide C.sodium oxide D.sodium (II) oxide

13. Name FeCl 3 A.iron (I) trichloride B.iron(III) chloride C.iron trichloride D.iron chloride(I)

14. What is the formula for iron(II) nitride ? A.FeN 3 B.Fe 2 N 3 C.Fe 3 N 2 D.Fe 2 N

15. Name P 2 O 5 A.diphosphorus pentoxygen B.phosphorus (V) oxide C.phosphorus oxide D.diphosphorus pentoxide

16. Naming with oxyanions replacing NM EXAMPLES OF OXYANIONS PO 4 3- formula name phosphate Oxyanion charge -3 SO 3 2- sulfite -2 NO 3 1- nitrate

17. M + NM example (U-name-it) BaCl 2 Barium chloride M + OXY example (models M+NM pattern) Ba(NO 3 ) 2 Hint: Cl is -1Hint: NO 3 =nitrate is -1 Barium nitrate

18. TM + NM example (U-name-it) CuO Copper(II) oxide TM + OXY example (models M+NM pattern) Cu(CrO 4 ) Hint: O is -2Hint: CrO 4 =chromate is -2 Copper(II) chromate

19. In-class Board practice with OXYANIONS