Notes CH 5
Electron Configurations
telling
electrons
where they
can go!!
Electrons.. Where are they?
And why do we need to
know?
The chemical behavior
of an element is
determined by the
number of electrons
and how they are
arranged.
Bohr’s model
Helped explain why elements give off
certain colors of light (excited electrons
jumping to lower energy levels)
Electrons travel in specific energy
“orbits” but not in between them.
3rd
Electron can be
here
2nd
1st
But not here
Review…Bohr’s model of the atom
Each level has a certain
number of e1st = 2
2nd = 8
3rd = 18 (or 8)
4th = 32 (or 18 or 8)
5th = 32 (or 18 or 8)
6th = 18 (or 8)
7th = 8
**Note= last level cannot
have more than 8 valence e-
nucleus
Energy
levels
Bohr models of various atoms.
1.
Draw (or write) the Bohr
sequence for Calcium
(20)
2.
Give the # of valence
electrons (last level)
3.
Tell if will lose e- (like
metals, have less than 4)
or gain e- (like nonmetals, have more than 4)
or metalloids (either gain
or lose)
4.
Give the isotope symbol
Bohr models of various atoms.
1.
Draw (or write) the Bohr
sequence for Bromine
2.
Give the # of valence
electrons (last level)
3.
Tell if will lose e- (like
metals, have less than 4)
or gain e- (like nonmetals, have more than 4)
or metalloids (either gain
or lose)
4.
Give the isotope symbol
Example
For all the element Bromine (35):
1) Draw (or write) the Bohr sequence
2 – 8 – 18 - 7
2) Give the # of valence electrons
7
3) Tell if will lose e- (like metals) or gain e(like non-metals)
Will gain one electron
4) Give the ion symbol and charge
80
35 Br
-1
Question
Why do elements give off different colors of light
when heated? (need to know for LAB on Friday)
Some of the electrons (ground state) gain enough
energy from the heat to jump up to a higher energy
level (excited state). They are unstable here so they
jump back to a lower level and give off the energy
gained as photons. The photon’s energy determines
the frequency (and color) of light.
Flame tests and Spectra
Each element has a characteristic pattern of light that
it emits.
This can be used as a “fingerprint” for identification.
Niels Bohr’s Atomic model
Yes! It’s Bohring!
http://videos.howstuffworks.c
om/hsw/5787-niels-bohrsatomic-model-video.htm
Assignment = Simple atomic models
1. a. Bohr’s model
b. isotope symbol
c. charge
For these elements: S, As, Sr, Ar, Cl, Ag
2. Pg 145 # 10, 12-14 (show details for
calculations)
Modern views of the Atom
Electrons can act as particles and sometimes as waves
(dual nature)
Electrons travel in paths that look like clouds. The size
and shape of these depend on how much energy the
electrons have.
The 4 quantum numbers describe the location of the
electrons:
Principal QN (symbol “n”) refers to the number of
energy levels and indicates the relative size and
energies in the atomic orbitals.
Secondary or angular QN (symbol “l” ) indicates the
sublevel (s, p, d, or f)
Magnetic QN (symbol “m”) indicates the orbital the
electron is in (px, py or pz)
Spin QN (symbol “s” ) indicates the direction the
electron is spinning (left or right)
There are 7 energy levels divided into different
sublevels which are divided into orbitals.
An orbital is the space where two electrons
travel. They have the shape of the sublevel but
different orientations.
Sublevels:
s = 2 e- max p = 6 e- d = 10 e- f = 14 e-
“s” =
“p” =
Shape of d
Shape of f
Mind Blowing!!
Just imagine an atom with
for example 92 electrons like
Uranium. All are whizzing
around the nucleus at the
speed of light in different
shaped paths.
Video orbitals!
http://www.youtube.co
m/watch?v=KjNgq16jEY&feature=rel
ated
Just read
Electron configuration (long form)
This gives MORE information about predicting
properties.
The placement of an elements electrons is written as:
4th Energy level
6 electrons
6
4p
These add up to
total # of e-
Sublevel p
2
1s ,
How many total
electrons?
2
2s ,
6
2p ,
What element is it?
2
3s ,
6
3p
There are rules!
Aufbau rule: Electrons occupy the lowest energy
orbitals first.
Hund’s rule: States that single electrons must
occupy separate orbitals before pairing up.
Pauli Exclusion Principle: No two electrons in an
atom have all 4 quantum numbers the same. One
quantum number must be different. Aka  SPIN!
The “Arrow” Diagram
Electrons arrange
themselves in orbitals of
increasing energy.
Examples:
N
Al
K
This is on page 160.
Br
s = 2 p = 6 d= 10 f = 14
Ag
Take sulfur for example. It has an atomic number of
16, so it has 16 electrons. Let’s put these in order.
1s2, 2s2, 2p6, 3s2, 3p4
Valence e-?
_____ on level ____
How many e- lost/gained? _______
Charge of ion? _______
Check it! it should be in group 6 and on period 3
……is it?
Practice
Write the electron configuration (long form) for:
Arsenic ____ electrons
And for arsenic’s ion? (As3-)
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p3
Practice
Write the electron configuration (long form) for:
Silver
____ electrons
And for silver ion?
Hint: it loses one e-)
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6 , 5s2 , 4d9
HW
pg. 160 #21 & 22 and WS
Bellringer
Turn in HW pg 160 (21, 22)
A) Write the long-form
electron configuration for
V (23)
B) tell how many valence eit has
C) give the ionic charge
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d3 ; 2; 2+
Bellringer 2
1. Which QN symbol means “main energy
level”?
n
2. Which 4 symbols means “sublevel”? s, p,
3. Write the long configuration for Se (34)
1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p4
4. How many valence electrons are there?
5. What will the charge of the ion be?
2-
6
d, f
Electron configuration
Shorthand version (Noble gas
version)
Ex Silver = [1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10,
4p6 ], 5s2 , 4d9
Take the previous Noble Gas and substitute
[Kr], 5s2 , 4d9
Or do directly from PT……
Copy or memorize… or
Google
→
“f” before “d”
←
7p
d (n-1) and f (n-2)
→
More….
1.
Oxygen
2.
And O2- ??
3.
Arsenic
4.
Aluminum
5.
And Al3+ ??
6.
Europium
More Practice
Fe
3+
F1Na1+
N
3-
Rules? …..What rules?
1. Electrons can behave as a particle but also
have wavelike behavior (dual-nature by
DeBroglie)
2. Electrons will be in the lowest available
energy position first. (Aufbau rule)
3. Electrons will be in separate orbitals (same
energy) before pairing up. (Hund’s rule)
4. Electrons will orient themselves to have
opposite spins if in same orbital. (Pauli rule)
What??? Let’s try applying this…..
Orbital diagrams
We use boxes to indicate
the orbitals
1s
2s
2p
3s
4d
And arrows to indicate each electron
Practice
Let’s do oxygen (8e-)
1s
2s
2p
3s
3p
So…it has 2 unpaired electrons to use
for bonding with other elements.
And now aluminum (13 e-)
1s
2s
2p
3s
3p
More
Let’s do Neon (10 e-)
1s
2s
2p
3s
3p
And now chlorine (18 e-)
1s
2s
2p
3s
3p
And
Vanadium
Selenium
Bellringer
1.
Turn in Homework
2.
What is the long form electron configuration for sulfur? See pg 160
3.
How many valence electrons does it have and on what level?
4.
How many e- does it need to have a complete valence level?
5.
What is the short form and orbital diagram for Te (52)?
6.
What is wrong with this?
[Ar] 4s2, 3d6 , 4p3
Practice
a) Bohr model
b) long form
c) Short form
d) Orbital diagram
e) Valence e-
Pd
Ge
Pb
Homework
a) Bohr model
b) long form
c) Short form
d) Orbital diagram
e) Valence e-
At (85)
K(19)
Se (34)
P(15)
Video
http://www.youtube.com/watch?v=xH1
k1dtgiVY
Electron Dot Diagrams
Only show valence electrons
Examples:
Assignment
Pg 167 (Glencoe)
# 81, 85, 86, 87, 90
To turn in!
Write the:
a) short electron configuration.
b) # of valence e
c) # e- lost/gained
d) charge of ion
1.
2.
3.
4.
iodine
hafnium
francium
xenon
5. helium
6. boron
7. yttrium
8. tin
Exit slip
For the element Phosphorous (P) and
Bromine (Br)
Write the:
a) short electron configuration.
b) # of valence e
c) # e- lost/gained
d) charge of ion
e) orbital diagram
Bellringer
1. What is the long form electronWhich
2.
3.
4.
5.
symbol means
“main
energy
level”?
3 or 4
Which symbol means “sublevel”? s, p or
Which symbol means “number of
electrons”? 2, 3 or 10
How many valence electrons are there? 5
What will the charge of the ion be? 3-
[Ar] 4s2, 3d10 , 4p3
d
Bellringer
1. What symbol is used in orbital diagrams to
2.
3.
4.
5.
show one electron? An arrow
What rule says that electrons will occupy the
lowest energy orbitals first? Aufbau
Who first stated that electrons can behave
both as a particle and as a wave? DeBroglie
What do we call the distance on a wave for a
complete cycle? Wavelength
What do we call the height (energy) of a
wave? Amplitude
To turn in!
Write the:
a) Bohr sequence (ex 2-8-3)
b) long electron configuration.
c) # of valence e
d) # e- lost/gained, charge of ion
1.
2.
3.
4.
Palladium
Indium
Gadolinium
Dysprosium
5. Argon
6. Molybdenum
7. Polonium
8. Radium
EMR (electromagnetic
radiation)
All wavelengths = from gamma rays (very
short=high energy) to radio and TV
(long=low energy).
All types of EMR travel at the speed of light
Are emitted when excited electrons jump to
lower energy levels.
A “piece” or quantum of EMR is called a
photon.
or crests
Review EMR
waves
A Solving problems Show all your work, write the equation and
be sure to indicate your units
c= v
and
Ephoton = h v
speed of light is c=3.00 x 108 m/s
Planck’s constant is h = 6.626 x 10-34J s
1) What is the wavelength of electromagnetic radiation with a
frequency of 8.77 x 1014 Hz?
2) What is the frequency of light that has a wavelength of
400. nm?
More
Calculate the frequency for yellow light See handout
600 nm = 600 x -9 m
5.00 x 10
14 1/s
Calculate the frequency for a bar-code laser.
660 nm = 660 x 10 -9 m
4.55 x 10
Calculate the energy for an X-ray photon (3.88 x 10
17
14 1/s
Hz)
2.57 x 10
-16
J