October 5th, 2015
• What is the atomic mass of hafnium if, out of every 100 atoms, 5 have mass 176, 19 have mass 177, 27 have mass 178, 14 have mass 179, and 35 have mass 180.0?
Electron Configurations: Chapter 5 sections 5.2 & 5.3
Why should I care?
The number of electrons
surrounding the nucleus determines
all the chemical properties.
Electron Configuration: Shows the most stable arrangement of electrons around the nucleus.
1s1Energy Level Sublevel
# of electrons
“S” Sublevel = Sphere Shaped
1 orbital
Holds two (2) electrons
“P” Sublevel = Dumbbell Shaped
Three (3) orbitals
Holds two (2) electrons in each orbital (6 electrons total)
“D” Sublevel = Shaped like a cloverleaf
Five (5) orbitals
Holds two (2) electrons in each orbital (10 electrons total)
“F” Sublevel = Balloon Shaped
Seven (7) orbitals
Holds two (2) electrons in each orbital (14 electrons total)
Sublevel Orbitals Electrons
s 1 2
p 3 6
d 5 10
f 7 14
H = __ 1s
Electron Configuration
Orbital Filling Diagram
H = 1s1ATOMIC NUMBER
Pauli Exclusion Principle:
2 electrons in an orbital must have opposite spin
He = __ 1s
Electron Configuration
Orbital Filling Diagram
He = 1s2
1st Energy Level
2nd Energy Level
3rd Energy Level
4th Energy Level
5th Energy Level
6th Energy Level
s
s
s
s
s
s
p
p
p
p
p
d
d
d
d
f
f
f
Can Hold:
Li = __ __ 1s 2s
Electron Configuration
Orbital Filling Diagram
Li = 1s22s1
Aufbau Principle: Electrons are stable in the lowest energy level possible
Aufbau comes from the German word aufbauprinzip which means building up.
Be= __ __ 1s 2s
Electron Configuration
Orbital Filling Diagram
Be= 1s22s2
B = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
B= 1s22s22p1
Hund’s Rule: One electron enters each orbital until all have one of same spin, then pairs will be added.
C = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
C= 1s22s22p2
N = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
N = 1s22s22p3
O = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
O = 1s22s22p4
F = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
F = 1s22s22p5
Ne = __ __ __ __ __ 1s 2s
2p
Electron Configuration
Orbital Filling Diagram
Ne = 1s22s22p6
Rule of Eight:
An atom is most stable when it has 8 electrons in its outer
shell, called an Octet
1
2
3456
7
1
2
3456
7
__ __ __ __ __
3d
__ __ __ __ __ __ __
4f
1
2
3456
7
Assignment
• Complete Electron Configurations & Orbital Diagram practice (WS)
• Finish atomic history (WS)
• Book Readings are due Friday.