Warm-up
1. Choose the atom in each pair that has
the greater ionization energy.
a) P Ar
b) Ca Be
2. Circle the atom in each pair that has
the greater electronegativity.
c) Br As
d) Li O
March 4th, 2015
Electron Configuration
Electron basics
• Carries the negative charge of the atom
• Has mass of 0.0006 amu (6/10000 mass of a
proton)
• Located in region around (outside) nucleus
• Has a spin that creates a magnetic field
– Either spins clockwise (“up”)
– Or counterclockwise (“down”)
• Atoms are electrically neutral, therefore, the
number of electrons = number of protons.
Bohr Model
•
Niels Bohr
–
•
planetary model
electron orbits around the
nucleus
• orbit 1 closest to the nucleus
• Orbits increase in size and
number as they get further
away from the nucleus.
– The orbit number is
known as the Principal
Quantum Number (n).
Bohr Model
•
•
•
•
Orbits have a fixed
radius.
lowest energy is closest to
the nucleus
increases as the orbits get
further away
Electrons absorb or
emits energy when they
change orbitals
∆E = Ef – Ei
Quantum Theory
Increasing energy
Fifth
Fourth
Third
Second
First
• Discrete Electron
Energy Levels
• Further away
from the nucleus
means more
energy.
• There is no “in
between” energy
Quantum Mechanics
In quantum mechanics, the electrons occupy
specific energy levels (as in Bohr's model) but
they also exist within specific probability
volumes
called
orbitals
with
specific
orientations in space. The electrons within
each orbital has a distinct spin.
n = The principle quantum number
Describes the possible energy levels and
pictorially it describes the orbital size.
n = 1, 2, 3…. where an orbital with the value of 2 is
larger than an orbital with the value of 1.
1s
2s
Modern Model of the Atom
Figure 7.12
Modern Model of the Atom
• Schrodinger wave equation
• electrons occupy orbitals, not
orbits
– Orbitals
• Three dimensional
regions in space where
electrons are likely to be
found
• not a circular pathway
– Principal energy level, n
• Orbitals of similar size
Figure 7.11
Orbitals
Figure 7.13
•
•
different shapes and sizes.
– Lower energy orbitals are smaller.
– Higher energy orbitals are larger; further away from the
nucleus.
s, p, d, and f are sublevels
s Orbitals
Figure 7.14
p Orbitals
d Orbitals
Nodes
07_105
07_106B
Node
p
z
1s
z
z
2s
(a)
3s
y
s
y
x
x
2px
y
x
2py
2pz
(b)
1s
2s
(b)
07_108B
3s
z
z
y
z
y
07_109
z
z
z
y
x
x
x
x
y
x
y
fz3- 3 zr 2
dxz
dyz
z
z
y
d
z
x
dx2 - y2
fy3 - 3yr 2
5
5
z
f
z
y
y
x
(b)
z
y
fx3- 3xr 2
5
dxy
x
x
dz2
x
y
fxyz
x
y
fy(x2 - z2)
x
y
fx(z2 - y2)
fz(x2 - y2)
Energy Levels
• Each level n has n sublevels
• Each sublevel (s, p, d, f) corresponds to orbital
shapes and orientations:
– Sublevel s contains one s orbital
– Sublevel p contains three p orbitals
– Sublevel d contains five d orbitals
– Sublevel f contains seven f orbitals
Electron Placement
3. Energy Levels
• As Bohr theorized, we believe electrons have certain levels
of energy (level = n = 1, 2, 3, etc.)
• For each level of energy, there are sublevels of energy:
Energy level
n=1
n=2
n=3
n=4
Sublevels
1s
2s, 2p
3s, 3p, 3d
4s, 4p, 4d, 4f
Multielectron Orbital Diagram
• In the multielectron atoms, the sublevels within a
principal energy level have different energy levels.
Summary
Starts at
energy
level
Sublevel
# of shapes
(orbitals)
Max # of
electrons
s
1
2
1
p
3
6
2
d
5
10
3
f
7
14
4
Orbital Diagram Rules
– Aufbau principle
•
–
Pauli exclusion principle
•
–
A maximum of two electrons can occupy each orbital, and they
must have opposite spins.
Hund’s rule
•
•
•
Electrons fill orbitals starting with the lowest-energy orbitals until
all the electrons of the atom have been accounted for.
Electrons will spread themselves out in a sublevel (equal energy
orbital) so that a maximum number of unpaired electrons result
If a sublevel were a bus, electrons wouldn’t share seats unless they
had to.
Electrons are always filled in their ground state, or
lowest energy state.
Filling Orbital Diagrams
Pg. 251 (Carbon’s orbital diagram)
Electron Configuration
Electron configuration is a shorthand
notation for describing the arrangement
of the electrons about the nucleus.
General Format using the quantum numbers:
n = principle quantum number
n l e- l = angular momentum quantum
number
e- = number of electrons
RULES:
1. Fill the lowest energy levels first.
Lowest
1s 2s 2p 3s 3p 4s 3d 4p
2. No more than two electrons per orbital.
Electron Configuration
Examples:
H: 1s1
He: 1s2
Li : 1s2 2s1
Co: 1s2 2s2 2p6 3s2 3p6 4s2 3d7
Br: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
The Principal Quantum Number and
Sublevel on the Periodic Table
Figure 7.21
Our Map
or
Seating
Chart for
Electrons
Using the Periodic Table for Electron Configurations
• Blocks contain elements with the same highest-energy sublevel.
An Example of writing Electron
Configuration
using the Periodic Table
P = 1s22s22p63s23p3
Mn= 1s22s22p63s23p64s23d5
Content & Language
Objectives
Warm-Up
Electron Configuration
HW: Coloring Activity
March 4th, 2015