1. California Admitted into US (1850)
Reading:
Make sure you have read ALL of chapters 3 & 4
Mastering Chemistry
Assignment #3
Chapter 4 #’s 16,17,20,36,38,46,50,52,54,56,72-88 evens, ,102,110,117
Due Sunday 9/13/09 by 11:59 PM
Average student took ~ 2 hours

2. Nomenclature Nomenclature lists #1, #2… phosphate = PO43-
sulfate = SO42-
nitrate = NO31-
chlorate = ClO31-
EXTRA CREDIT OPPORTUNITY

3. We left off at… Atoms are made up of p+, no, and e-
# of p+ = atomic number, cannot change for elements
# of no CAN change within an element
Atoms are NEUTRAL!!!!!
ANY charged particle is called an ion
Losing e- gives POSITIVELY charged ion (cation)
Gaining e- gives a NEGATIVELY charged ion (anion)
PT can be broken into different categories

5. My Atom Broke Subatomic Particles Nucleus Protons – p+ Neutrons – no
Carry a single positive charge
Number of p+ = ATOMIC NUMBER
Neutrons – no
No charge
# can vary from atom to atom
Roughly the same size

8. Mass of no about equal to mass of p+
Do each of these atoms have the same mass?
Isotopes: Atoms having the same atomic number, but different atomic masses

9. A E S 16 Z Atom notation Mass number = # p+ + # no Symbol of element
Atomic number

10. 32 A S E 16 Z 33 S 16 32 S 16 34 S 16 36 S 16 Shorthand: Sulfur-33

11. 208 Pb 82 54 Fe 26 63 Cu 29 Give the atom notation for the following:
1) an atom with 82 p+ and 126 no
2) an atom of iron with 28 no
3) an atom of element 29 having 34 no
208
82 p no = Pb 82 54 Fe 26 63 Cu 29

12. Atomic Notation
Atomic Number
Mass Number
Number of p+
Number of no
Number of e-
83Bi
209 83
209 83
126 83
53I
127 53
127 53 74 53
24Cr 53 24 53 24 29 24

13. Information from the Periodic Table
(atomic number) 20 =
= amu (atomic mass)
(atomic number) 8 =
= amu (atomic mass)

14. Atomic Masses Measured in the unit amu 35Cl = 34.9689 amu
Stands for atomic mass unit
Defined as 1/12th the mass of a 12C atom
35Cl = amu
50V = amu
79Br = amu
Are these what the P.T. say?

15. All Isotopes are NOT Created Equal
Weighted averages

16. All Isotopes are NOT Created Equal
Atomic mass is a WEIGHTED average of isotopes
HUH??
Final
Quiz
Possible
300 20
You earned
285
(95.0) 10
(50.0)
average =
(score1 x weight1) + (score2 x weight2) = grade
(95.0 x ) + (50.0 x ) = 92.2%

17. All Isotopes are NOT Created Equal
Weighted averages
An equation (oh crap)
35Cl = amu
Abundance = 75.77%
37Cl = amu
Abundance = 24.23%
These must be the only 2 isotopes... Why?

18. All Isotopes are NOT Created Equal
35Cl = amu
Abundance = 75.77%
37Cl = amu
Abundance = 24.23%
=0.7577
=0.2423
Please calculate the average atomic mass of chlorine for Friday’s lecture. (this will NOT be collected)