1. Homework 3 due today in class
Homework 4 posted- due Wednesday 14 Feb

2. What is the correct formula for Copper(II) Acetate?
Cu(C2H3O2)
Cu2(C2H3O2)
Cu(C2H3O2)2
Cu(C3H2O3)

3. What is the formula for Chromium (IV) Phosphite?
Cr3(PO3)4
Cr4(PO3)3
CrPO3
Cr(PO3)4

4. What does Dalton’s atom look like ??
The Big picture, Part 3
What does Dalton’s atom look like ??
What’s in the atomic box ?

5. Dalton’s implicit assumption: atoms are round balls of different size and mass that can stick together.

6. The real and evolving inside picture of the atom (2.4-2.5)
Thomson Model
1897
Bohr Model
1913
Philosophical
Magazine Series 6,
21, (1911)
Philosophical Magazine Series 6
(1913)
Philosophical Magazine 44, 295 (1897)

7. Nuclear radius* ~10-15 meters
Dimensions of the Rutherford model
Nuclear radius* ~10-15 meters
Electronic cloud (e-) radius
~ meters
In neutral atoms: # p+ = # e-
*Contains protons(p+) and neutrons (no )

8. Wazzat mean ? R(electron) ~ 100,000 R(nucleus)
The surprising dimensions of the atom
R(electron) ~ 100,000 R(nucleus)
Wazzat mean ?

9. Atom dimensions in familiar terms.
Metaphor 1: Old Yankee Stadium, the Bronx 3”
Electrons start here (~2.4 miles past cheap seats)
Baseball as nucleus
Show how calculation was done on board

10. Nucleus(+)
~ dimension of electronic cloud (-) (2.4 mile radius from baseball nucleus)
Stadium at 1. E. 161st st., Bronx NY 14051

11. Metaphor 2: Metaphor 3: Answer: 50X POP CAN WITH STRING + PENCIL DOT…
HOW FAR AWAY IS THE ELECTRON FROM THE PROTON (DOT) {0.02 CM DIAMETER}?
Metaphor 3:
CUT UP 20 cm STRIP OF PAPER…HOW MANY CUTS TO REACH ATOMIC SCALE?
Answer: 50X

12. Masses of subatomic pieces
Mass (g)
Relative mass
proton
1.67*10-30 1
neutron
1.67*10-30 1
electron
0.0005
9.11*10-34

13. 165 lb running back=proton weighs ~ 2000 eggs
Proton mass
Metaphor 4: proton vs. electron mass
Electron mass
165 lb running back=proton weighs ~ 2000 eggs

14. Metaphor 5: a penny for your thoughts….
proton vs. electron mass
x 2000
=$20.00
~3.0 g
x 2000
=6000 g
=13 lbs of pennies

15. Volume comparison
The electron cloud volume is 1015 times bigger than the nuclear volume
Metaphor 6:
Volume occupied by nucleus
Volume occupied by electrons

16. Electron cloud density is equivalent to 1 dust speck smeared out into a packing box…matter is composed mostly of nothing….

17. Modern View of Elements (p. 47)
. All atoms of a given element have the same proton count.
Atoms of different elements have different proton counts.
Modern twist: a given element can have different neutron counts in the nucleus (isotopes) and still be the same chemically=> same element can differ in weight !

18. How the entries on the Modern Periodic Table reflect the `Modern’ definition of an element
proton count
Average mass of protons and
neutrons

19. BOYLE & DALTON WERE WRONG (A LITTLE)
“All atoms of a given element weigh the same”
…THEY didn’t know about isotopes and neutrons
…but they can be forgiven…in 1805 equipment was little better than kitchen ware….
Dalton’s measured mass
Correct average mass 12 14 16 23
12.01
14.01
15.99
22.99 C N O Na