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Homework 3 due today in class

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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


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