November 6, 2009
•E X A M # 3 M O N D A Y , N O V E M B E R 9 T H
•R e s o u r c e s p o s t e d o n c o u r s e w e b s i t e :
•Study
Guide
•Practice
Problems (Study group problems and answer
key)
•Video
•T o d a y :
Review
Periodic Properties
Electron Configurations and the Periodic Table
 Chromium and copper are anomalies
Cr
Cu
Periodic Trends
 How does the electron configuration lead to the
properties of an element?
 Basic Properties
Size
 Ionization Energy
 Electron Affinity
 Ion Size (electron configuration of ions)

 Keep in mind Coulomb’s Law (force between
charges):
q
q
1
2
Force

k
e 2
r
Trends in Orbital Energies
Trends in Orbital Energies
Why do energies decrease moving left to right?
 Overall attraction of nucleus for electrons
determines energies and size
Less attraction  higher energy
 Attraction dependent on distance and charge
 Effective nuclear charge (Z*)
Z*= Z – S
Z=nuclear charge
S=shielding

q
q
1
2
Force

k
e 2
r
Atomic Size
What happens to the force of
attraction between the outermost
electrons and the protons in the
nucleus as you go down a group?
… as you go across a period?
q
q
1
2
Force

k
e 2
r
Which atom is the smallest?
1. H
83%
2. He
3. Cs
4. Rn
13%
3%
1
2
3
1%
4
Which atom is the largest?
1. K
81%
2. Ca
3. Rb
4. Sr
12%
4%
1
4%
2
3
4
Electron Configurations of Cations
Transition Metal Cations: Lose s electrons first
Ion Size