2. What is the correct electronic configuration for Cl ?
1s22s22p63s23p5
[Ar] 3p5
[Ne] 2s23p5
1s22s22p63p4

3. What is the correct electronic configuration for Fe2+ ?
[Ar] 4s2 3d4
[Ar] 3d6 4s0
[Ar] 3d4 4s2
[Ar] 3d5 4s1

4. What is the correct electronic configuration for Se ?
[Ar] 4s2 3d10 3p4
[Ar] 3d10 4s2 4p4
[Ar] 3d10 4s0 4p6
[Ar] 3d10 4s3 4p3

5. What is the correct, abbreviated, electronic configuration for Cu+1 ?
[Ar] 4s0 3d10
[Ar] 3d9 4s1
[Ar] 4s13d10
[Ar] 3d10 4s0

6. Dalton, Lavoisier and Avogadro
Where we’ve been….
Dalton, Lavoisier and Avogadro
Moles by weight and gas law
Chemical compositions
reactions

7. Where we’ve been….
Thomson, Rutherford & Bohr 1910
1) Atomic structure & dimensions
2) p+no , e- bookkeeping
3) Crazy quantum models

8. In the land of the spectroscopists:
Where we’ve been….
In the land of the spectroscopists:
1s2 2s2 2p6 3s2 3p4 ……
Describing atoms by electronic configurations implied by observation and predicted by Periodic table
spectroscopy
`fugetabout theory….let the line spectra rule or I breaka your face !

9. The Americans land….here
Reading: Chapter 8
pp ionic model
pp Lewis rules & covalent
compounds
pp exceptions
pp formal charge, resonance
pp VSEPR theory

10. Ionic compound prediction redux:
I haz my `ion’ you

11. CONDUCTIVITY DEMO…. NaCl HOW DO YOU KNOW A COMPOUND IS IONIC???
If it lights up the light bulb, it’s ionic

12. In ionic bonding, opposites attract….and hook up+ -

13. Is there a simple pattern here ??
Trends in binary ionic and near-ionic formulas
LiCl
Li2O
Li3P
Is there a simple pattern here ??
Trends down a column
Ma Xb …all M’s combine the same for a given X
NaCl
Na2O
Na3P
KCl
K2O
K3P

14. The rule of 8 ( early version of the`octet rule’)
rule of 8: sum of column numbers in elements combined in many simple binary compounds1 add to 8
Ca + O  ?
CaO
Li + Se ??
Li2Se
2*1+6=8
col
2+ 6=8
col
H3N or NH3
Is it safe to assume this works all the time ????
H + N ?
Col
3*1+5=8
1simple ionic compounds ~formed
of column 1- 2 elements (cations)
with columns 5-7 (anions)

15. BUT…what about… Actual formula Mg3N2 Mg + N ??? col 2 5
Rule of 16 ??? 3*2 +2*5=16 =2x8
(ICKY…too much math for us Americans) 
Actual formula Mg3N2

16. Rule of 8 is too simplistic.
Must look some more at Periodic Table trends

17. HINT #1: The Periodic Trend of Pauling’ Electronegativity (=electron suckativity) scale reveals a cliff….
???

18. HINT #2: the curious case of column 8

19. What’s so curious ?? None Nada 8 Noble gas chemistry
The “Noble” Elements are utterly stable …
…And what’s with this number 8 ??
Noble gas chemistry
None
Nada
Noble…because like all aristocrats they have nothing to do with any of the lower class elements.

20. CaO Ca= [Ar]4s2 O=[He]2s22p4 Ca2+=[Ar] O2- =[He]2s22p6=[Ne] Example:
The crazy stability of the noble gas electronic configuration is the key to a model for predicting ionic and near-ionic compound formulas.
Example:
CaO
Ca= [Ar]4s2
O=[He]2s22p4
Lose 2 e-
gain 2 e-
O2- =[He]2s22p6=[Ne]
Ca2+=[Ar]

21. Lewis dot pix for atoms Ca= [Ar]4s2 O= [He]2s22p4 = [Ar]+2 -2 Ca O Ca O Ar Ne
[CORE]
VALENCE
Ca= [Ar]4s2
O= [He]2s22p4
= [Ar]
= [He]2s22p6=[Ne]

22. Cations: count left to col 8 for + charge
A quick visual way to know element charges
Cations: count left to col 8 for + charge
Anions: count right to col 8 for - charge -3 +2
…but don’t do this with transition metals

23. Knowing cation and anion charges lets us predict binary compound formulas (you’ve already seen this)
EXAMPLE:
Predict compound made of Na and S +1 -2
1)FIND PREFERRED CHARGES Na S 2 1
2)“CROSS” CHARGE MAGNITUDES

24. Ca + Cl CaCl2 Al + O Al2O3 B + N BN K + S K2S Mg+ As Mg3As2
In-Class practice:
Deducing formulas for ionic compounds
Ca + Cl
CaCl2
Al + O
Al2O3
B + N BN
K + S
K2S
Mg+ As
Mg3As2

25. Another dumb Doc question:
“If the atoms in a compound don’t light up the bulb (not ionic) then how are the electrons distributed if not like ionic case ??”

26. * We know how to use the fancy math…but our `style ‘ is visual and practical
The Americans land…
G. N. Lewis 1925 AD: Teaches us how to use the Periodic table to rationalize ionic and covalent compound formulas without breaking a sweat…The Big Kahuna of an American-style Chemistry that looks at the big picture and uses simple, intuitive models .
(sans calculations …)* Enter the Lewis Octet Rule

27. Legacies of the American chemist: Gilbert Newton Lewis
Gilbert Newton Lewis American Chemist UC Berkeley “at work” ~1930
Before Lewis: UC Berkeley Chemistry Building ~1915

28. Chemistry `Quad’
UC Berkeley 2013
+ more `on the hill’ at L-L Labs

29. The House that Lewis Built: Lewis Hall of Chemistry
As young chemistry
nerd …Young Doc
Fong sits in here
staring every day
at a 4’x 6’ photo of…
The House that Lewis Built: Lewis Hall of Chemistry
UC Berkeley

30. American chemistry rules, baby !
Chemistry factoid:
Since 1901, Americans have been awarded the Nobel Prize in chemistry 71 times, mostly after the time of G.N Lewis.
The next closest country is Great Britain with 17.
American chemistry rules, baby !

31. All bonds contain two electrons.
Lewis `octet’ model (see also pp. 378)
The Entire Lewis model In a nutshell:
All bonds contain two electrons.
All elements except H and He1 seek an outer (valence) shell of 8 electrons.
If you can –minimize formal charge.
For elements from P onwards, you can break the octet rule and use rule 3.
1H and He are satisfied with 2 electrons= `duet’ rule

32. IN-CLASS BOARD OCTET RULE PRACTICE WITH::
Diatomics O2 N2 CO

33. What is the most likely Lewis structure for Cl2 ?
Double bonded so
Single bonded so:
Triple bonded so:

34. Multi-atom, neutral compounds1
IN-CLASS BOARD OCTET RULE PRACTICE (continued)::
Multi-atom, neutral compounds1
Tri, tetratomics CO2 H2O OF2 COCl2
1How do we know what bonds to what ?
Some rules of thumb:
Atoms closer to center of Periodic Table are in center of molecule
Molecules tend to be symmetric.

35. Diatomics O2 N2 CO tri, tetra-atomics CO2 H2O OF2 COCl2
IN-CLASS BOARD OCTET RULE PRACTICE WITH::
Diatomics O2 N2 CO
tri, tetra-atomics
CO2 H2O OF2 COCl2

36. Which structure below satisfies the Lewis octet rule for SOBr2 ?
all single bond
S=O double
S=Br double
None of the above

37. tri,tetra-atomics CO2  H2O  OF2 COCl2 
IN-CLASS BOARD OCTET RULE PRACTICE WITH::
Diatomics O2  N2  CO 
tri,tetra-atomics CO2  H2O  OF2 COCl2 
oxyanions NO3- CO SO42-

38. Which is the best structure for SO32- that satisfies the Lewis octet rule
All single S-O
1 S=O,2 S-O
2 =O, 1 S-O
All S=O

39. tri,tetra-atomics CO2  H2O  OF2 COCl2 
IN-CLASS BOARD OCTET RULE PRACTICE WITH::
Diatomics O2  N2  CO 
tri,tetra-atomics CO2  H2O  OF2 COCl2 
oxyanions NO3-  CO32-  SO42- 
Are we safe with the octet rule ???
Chemistry sucks…
The problem with octet rule:
H2SO4
(and SO2 SO3 SO42-
….. and many other examples)
stink up Lewis’s world

40. BEYOND THE OCTET RULE: FORMAL CHARGE
UGLY CHEMICAL FACT OF LIFE #1:
For elements starting with Si in the 3rd row, the octet rule is often broken.
EXAMPLE #1: BATTERY ACID (H2SO4)
Lewis octet prediction for H2SO4 structure
From Experiment
(Kuczkowski et. al. 1983)

41.   a) SO2 SO3 SO42- What is the octet rule prediction for SO2 ? VS.
We-work-it Examples where formal charge is minimized even if we break the octet rule.
a) SO SO SO42-
What is the octet rule prediction for SO2 ?  
VS.
+ and – formal charges
Lewis rule 3 says not good
No formal charges anywhere.
Lewis rule 3 says good !

42. Which is the best structure for PO42- that satisfies the minimize formal charge rule ?

43. U-Do-it Examples where we minimize formal charge or simply break octet rule (continued)
c) HClO ClO41-
What will be the Cl-O bond order in ClO4-?
( )/4 =7/4= 1.75

44. Non-Lewis ”got no choice” and radicals PF5 SF6 NO2
IN-CLASS BOARD OCTET RULE PRACTICE WITH::
Diatomics O2  N2  CO 
tri,tetra-atomics CO2  H2O  OF2 COCl2 
oxyanions NO3-  CO32-  SO42-
Non-Lewis formal charge rule
H2SO4  SO2  SO3 SO42- 
Any other problems ?
Yes !
Non-Lewis ”got no choice”
and radicals
PF5 SF6 NO2

45. Examples where we minimize formal charge or simply break octet rule because of the atom count on central atom.
PF SF6