ELECTRON
CONFIGURATION
HOW MANY ELECTRONS

ARE IN AN
ATOM?
In an ATOM,
# Electrons = # Protons = Atomic Number
3
6,7
Li
6.94
3 WAYS
TO
TELL HOW MANY ELECTRONS
Type
Pros
Cons
Atomic
Number
Quick and
easy, just look
at PToE
Doesn’t tell us about
arrangement of
electrons
3 WAYS
Type
Atomic
Number
TO
TELL HOW MANY ELECTRONS
Pros
Quick and
easy, just look
at PToE
Electron
Shows where
Configuration the electrons
are
Cons
Doesn’t tell us about
arrangement of
electrons
Doesn’t tell us
which ones can
bond
3 WAYS
Type
Atomic
Number
TO
TELL HOW MANY ELECTRONS
Pros
Quick and
easy, just look
at PToE
Electron
Shows where
Configuration the electrons
are
Lewis
Shows us how
(Electron)
many electrons
Dot Diagram can bond
Cons
Doesn’t tell us about
arrangement of
electrons
Doesn’t tell us
which ones can
bond
Doesn’t tell us total
electrons
3 WAYS
Type
Atomic
Number
TO
TELL HOW MANY ELECTRONS
Pros
Cons
Quick and
easy, just look
at PToE
Electron
Shows where
Configuration the electrons
are
Lewis
Shows us how
(Electron)
many electrons
Dot Diagram can bond
Doesn’t tell us about
arrangement of
electrons
Doesn’t tell us
which ones can
bond
Doesn’t tell us total
electrons
Yesterday
Today
Tomorrow
BACKGROUND INFORMATION
Energy Level – distance away from the
nucleus in which electron “resides”
-Think Bohr modelRepresented by 1, 2, 3, 4…
BACKGROUND INFORMATION
Orbital – regions in energy levels that
have similar shapes
Represented by s, p, d, f
BACKGROUND INFORMATION
s = Sphere
BACKGROUND INFORMATION
p = dumbbell
BACKGROUND INFORMATION
d = clover
BACKGROUND INFORMATION
f= complicated
Care to try??
STEPS FOR DETERMINING ELECTRON
CONFIGURATION
Step
1.
Find the atomic
number of the
element – this is #
electrons
Example - Li
Atomic # = 3
Li has 3 electrons
STEPS FOR DETERMINING ELECTRON
CONFIGURATION
Step
2.
Put the electrons in
their orbitals
Example - Li
3 electrons
STEP 2
Pauli Exclusion Principle – no more than
two electrons per orbital
STEP 2
Aufbau Principle – electrons fill lowest
energies first
STEP 2
Hund’s Rule - Electrons will stay
unpaired in each energy level for as long
as possible
STEPS FOR DETERMINING ELECTRON
CONFIGURATION
Step
3.
Write electron
configuration
Example - Li
3 electrons
STEPS FOR DETERMINING ELECTRON
CONFIGURATION
Report:
Energy
# electrons
Level Orbital
STEPS FOR DETERMINING ELECTRON
CONFIGURATION
Step
3.
Write electron
configuration.
Example - Li
3 electrons
1s22s1
EXAMPLE 2 -
Sulfur
Atomic # = 16
Electron Configuration: 1s22s22p63s23p4
EXAMPLE 3 -
Arsenic
Atomic # = 33
Electron Configuration:
1s22s22p63s23p64s23d104p3
EXAMPLE 4 -
Carbon
Atomic # = 6
Electron Configuration: 1s22s22p2
GETTING
INTO AN
EXCITED STATE
 An
electron in an excited state is in a
higher state (orbital and/or energy level)
than it usually is
 Ground
electron
state – normal level for an
EXCITED STATE
 When
the electron
receives energy it
jumps from the
ground state to a
higher level
 This
electron will
then fall back down
to the ground state
EXCITED STATE- WHAT’S

IT LOOK LIKE?
Remember the Lithium ground state?
1s22s1

What if we make an electron excited?

It’ll jump up in energy!
s
p
Excited State Lithium- 1s22p1
ON YOUR OWN

Try Helium, Oxygen, Calcium, and Bromine with a
Partner

Then do the rest BY YOURSELF!!

(Ask QUESTIONS when you need!!)