Announcements

1
Announcements

• To join clicker to class today
• Turn on the Clicker (the red LED comes on).
• Push Join button followed by 20 followed by
  the Send button (switches to flashing green LED
  if successful).

• Exam next Wed.
• Do not enter room until let in.
• Bring ID and Calculator.
• Quiz today sections 4.2-4.8.

Review

• yield
• limiting reactants
• composition
• empirical vs. molecular formulas.

2
Composition

• Molecules called ethylene and propylene are both
  14.372 by mass H. The rest is carbon (85.628).
• M(ethylene) 28.054 g/mol
• M(propylene) 42.081 g/mol
• Assume have 100 g of sample
• 14.372 g H/in sample (1.0079 g H/mol H) 14.259
  mol H/in sample
• 85.628g C/in sample (12.011 g C/mol C)7.1291 mol
  C/in sample
• nH/nC (14.372 mol H)/(7.1291 mol C) 2.0000
• 2 H/ C or CH2.

3
Composition

• Calculate formula mass
• (1 mole C/formula)(12.011 g C/mole C)
• (2 mole H/formula)(1.00794 g H/mole H) 14.027
  g/formula
• Calculate number of times formula mass goes into
  molecular formula
• MM(ethylene) 28.054 g/mole
• 28.054/14.027 2
• molecular formula C12H22 C2H4

4
Chapter 3- Atomic Structure(light interaction
with e-)

• Historical perspective
• Atom as () sphere with (-) electrons embeded
• Rutherford Experiment suggested dense nucleus
  because alpha particles scattered
• Evidence of Quantization from light
• Photoelectric effect (E h?) so electrons not
  ejected until Ephoton gt binding energy/work
  function. Extra energy ends up as kinetic
  Ephoton f K.E.
• Line spectra of atoms.
• Bohr Model of atom (orbiting electrons in
  specific orbitsproblem is should fall in)
• Wave Particle Duality (Debroglie relation
  ?h/mv) explains as the electrons are standing
  waves around nucleus.

5
Chapter 3 con't

• Modern model of atom
• Pauli exlusion principle and electron spin
  implies 2 electrons per orbital
• Fill from lowest energy up. n 1, 2, ... s
  before p.
• There are details use periodic table to determine
  actual configuration and do not forget about
  half-full and full subshells having extra
  stability.
• Understand how concepts of penetration and
  shielding explain relative energies of shells and
  subshells.
• Periodic trends and how they are related (atomic
  size, ionization energy, formation of ionic
  compounds)

6
Chapter 4- Composition of the Earth and an
Introduction to RXNs

• Composition of Earth (denser elements, mostly Fe,
  O, Si, Mg)
• Composition of early atmosphere (oxides of H, O,
  N, S)
• Naming of Simple compounds (binary ionic vs.
  molecular, polyatomic ions, and oxoacids, learn
  polyatomic ions)
• Calculating molar mass
• Balancing chemical equations (by inspection)
• Stoichiometry (Percent yield, Limiting reagents,
  Chemical analysis composition.)
• After balancing chemical equations all of these
  calculations require doing the following series
  of conversion given aA gt bB
• g A (MA)gt mol A (ratio fr/RXN)gt mol B
  (xMB)gt g B.
• For limiting reactants we do this process up to
  the moles of B stage for all reactants and only
  do the last step for the smallest moles of B.