83101 General Comments

1
8/31/01 General Comments

• Pick up 2 CAPA sets, due TUES and WED
• CAPA set 1 due today by 1100 PM
• Pick up copy of old foundation test
• Chem club picnic today - Smallenburg park
• Check out the ChemBoard comments by your
  classmates - have you added yours?
• ChemBoard as a homework resource

2
As you use the text book

• Section exercises have answers at the end of each
  chapter
• Problems are paired odd-even by concept
  1,2..11,12..33,34.. with each odd problem
  answered at back of book
• Problems grouped by section and concept
• Additional problems of all concepts
• Dont limit yourself to CAPA

3
Atomic theory philosophy to vision

• Greek Democritis, 400 BC, atmos gt indivisible,
  a common sense view
• John Dalton, 1800s experimental evidence that
  elements combine in fixed proportions. 3 g
  carbon4 g oxygen or 3 g carbon8 g oxygenno
  other combinations, regardless of the relative
  amounts of carbon and oxygen used

4

• Dalton had circumstantial evidence based on
  experiments - macroscopic observations were
  explained by atomic theory
• TODAY - we actually can see atoms with a scanning
  tunneling microscope (STM)

5
Features of atomic theory

• Matter is composed of tiny particles - atoms
• All atoms of an element have same chemical
  properties
• Atoms of different elements have different
  properties
• Atoms combine in whole number ratios to form
  compounds (molecules)
• In chemical reactions atoms recombine in
  different ways, but matter is conserved

6
Additional considerations of atomic theory

• Are atoms really the smallest particles?
• What holds atoms and molecules together?
• Requires a study of force and energy
• Gravitational
• Electromagnetic (Coulomb s law)
• Strong nuclear
• Weak nuclear

7
Study of atomic sub-structure

• JJ Thompson and the cathode ray tube
• Millikan and the oil drop experiment
• Rutherford - bouncing an artillery shell from a
  piece of tissue paper
• A theory of protons, neutrons and electrons
  explains the observations

8
Atomic Diversity

• A gt mass number (p n)
• Z gt element symbol
• Xgt atomic number (p)
• Isotopes gt same nuclear charge (p),different
  number of neutrons (n)
• Evidence of isotopes from mass spectroscopy

9
Charged atoms or molecules

• Cation gt positive charge
• Anion gt negative charge
• Charge due to imbalance of protons and electrons
• Ions cannot exist without having opposite ions to
  balance the charge

10
Ionic compounds solutions

• Group I 1 charge
• Group II 2 charge
• Group 17 -1 charge
• Ionic compounds regular pattern of - charge
  held together by electrical attraction
• Ionic solution ions are free to move and can
  therefor conduct electricity

11
For Monday..

• We DO have class
• CAPA 2 and 3 have some compound names - see
  section 3.2, we get there on Monday
• Have a great week-end, enjoy the summer