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Unit 3: The Electron Cloud and Electromagnetic Radiation
Unit 3 Page 1: Objectives!
Unit 3 Page 2: Electron Orbitals
Content Objective:
I can express the arrangement of electrons in atoms through
electron configurations
Criteria for Success:
I can define orbital.
I can explain how electrons are arranged within the electron
cloud utilizing the concept of orbitals.
Unit 3 Page 3: The Electron Cloud
Content Objective:
I can express the arrangement of electrons in atoms through
electron configurations
Criteria for Success:
I can state three rules that explain how electrons fill orbitals.
I can use those three rules to describe the electron configuration
for the atoms of any element in orbital notation.
I can relate the number of sublevels to each atom's main energy
levels, the number of orbitals per sublevel and per main energy
level.
I can use electron configurations and orbital notation to
determine quantum numbers.
Unit 3 Page 4-9: Standard Electron and Noble Gas Configurations
Content Objective:
I can express the arrangement of electrons in atoms through
electron configurations.
Criteria for Success:
I can describe the electron configurations for the atoms of any
element using standard notation.
I can describe the electron configurations for the atoms of any
element using noble gas notation.
I can determine the number of electrons, energy levels, and
valence electrons for any element on the periodic table.
I can use electron configurations to identify an element by
atomic number.
I can use electron configurations and orbital notation to
determine quantum numbers.
Unit 3 Page 10: Lewis Valence Electron Dot Structures
Content Objective:
I can express the arrangement of electrons in atoms through
electron configurations and Lewis valence electron dot structures.
Criteria for Success:
I can use the periodic table to determine how many valence
electrons an element has.
I can use a Lewis dot diagram to identify an element.
I can use the periodic table to draw the Lewis valence electron
dot structure for an element.
Unit 3 Page 11: Electromagnetic Radiation
Content Objective:
I can understand the electromagnetic spectrum and the
mathematical relationships between energy, frequency, and
wavelength of light.
I can calculate the wavelength, frequency, and energy of light
using Planck's constant and the speed of light.
Criteria for Success:
I can describe and interpret the electromagnetic spectrum.
I can calculate wavelength, frequency, speed, and the amount of
energy of a photon of light.
I can explain the relationships between energy, frequency, and
wavelength.
Unit 3 Page 12: Absorption and Emission Spectra
Content Objective:
I can express the arrangement of electrons in atoms through
electron configurations.
Criteria for Success:
I can explain the movement of electrons within atoms as they
absorb or emit different amounts of energy.
I can tell the difference between an atom in the ground state
and an excited state by the electron configuration.
Electron Orbitals
Unit 3 Page 2
A. The electron cloud consists of a complex arrangement of _______________________ within a series of main energy
________________________ and energy ____________________________.
1. Erwin _____________________________ used the hypothesis that electrons have a dual wave-particle nature to develop
wave _________________________ to describe electrons. The solutions to these equations describe the
__________________________ that make up the electron cloud.
2. ________________________, which are three-dimensional regions around the nucleus, indicate the probable location of
the electron.
a. A maximum of _________ electrons can fit in a single orbital.
3. Main energy levels indicate the general amount of __________________ and ___________________ from the nucleus a
given electron in an orbital possesses.
a. Each ______________, or period, on the periodic table indicates a main energy level and the maximum number of
electrons that can occupy that energy level.
4. Energy sublevels indicate the different _____________________ of orbitals that exist within the same main energy level
and these different shapes of electron orbitals are indicated by _______________________.
a. The s orbitals have a _________________ shape and there is only ________ s orbital in any given main energy
level and correspond to the first two columns on the periodic table.
b. The p orbitals resemble _________________ and there are a maximum of __________ p orbitals in any given
main energy level and correspond to the last six columns on the periodic table.
c. The d orbitals often resemble _______________ and there are ___________ d orbitals in any given main energy
and correspond to the transition elements on the periodic table.
d. Orbitals with higher energy than the d orbitals are labeled f, g…and so on in alphabetical order, but their shapes
are _____________________ to represent and are rarely used in general chemistry.
5. The electrons in the outermost energy level, or ______________________ level, are integral in determining how the atom
will react chemically.
a. The _________________ number (column) will help you determine how many valence electrons an atom has.
Is your teacher saying anything about this picture to the right
here? You should probably take notes on that. Maybe in this box
would be a good place.
The Electron Cloud
Unit 3 Page 3
Recall:
a)
b)
The atom has different ___________ _____________. Electrons in the 3rd _________ _________ have more energy AND are
farther from the nucleus than electrons in levels 1 and 2.
Within each energy level, there are _____________ that electrons stay in. These ____________ have different general
shapes associated with them.
s
p
d
f
c)
Each __________ (s, p, d, f) has a corresponding number of ____________ that are oriented around the nucleus on the axes.
d)
Each ______________ holds AT MOST 2 electrons.
With all of this in mind, we have a few systems that we can use to describe where an electron is within an atom, and how the electron
is moving around. These systems are really just different ways of formatting all the same information. We are going to learn to use
these systems first, and then we will recap how the systems work and give some vocabulary to it all at once.
The chart below is just the way we are going to start learning this information. We will actually keep coming back to this chart as we
gradually add more information to our knowledgebase.
There are two things that it will be helpful to know before we start filling out the chart. Notice that some parts are already highlighted
for you! That is because this is VERY IMPORTANT VOCABULARY.
A. Rules Governing How Electrons Fill Orbitals
1. The ________________________ _______________________ principle states that it is impossible to determine simultaneously
both the position and the velocity of an electron or any other particle. (Meaning you can’t know both WHERE IT IS and HOW IT’S
MOVING.) Despite this, we are able to determine the probable location of an electron and determine how electron orbitals are filled,
using some rules.
2. The _____________________ __________________________ principle states that no two electrons can be in the same place as
each other and moving the same way at the same time. (Later, we will learn that this will also mean they cannot have an identical set
of quantum numbers.)
I know there’s a lot of information here, but try to keep it all in mind! Here we go…
Element
Orbital Notation
Quantum Numbers
n=
H
l=
1 electron
ml =
ms =
Electron Configuration: _______________________
Noble gas configuration: ______________________
n=
l=
He
ml =
2 e-
Electron Configuration: _______________________
Noble gas configuration: ______________________
ms =
Remember the Pauli Exclusion Principle?
Two electrons cannot be in the same place and moving the same way at the same time! So if two electrons share an orbital, they
must be moving opposite ways!!
WHY???
Electrons that share an orbital are stuck in a small space together. But, they are still trying to repel each other because their
charges are the same! The most they can do to avoid each other is to __________ in ______________ ________________. So if
one is spinning “clockwise” (usually an _____ arrow), the next has to spin “counterclockwise” (usually a _____ arrow). Two
electrons in the same orbital can never spin in the same direction, so two arrows in the same blank can never point the same way!
n=
l=
Li
3 e-
ml =
Electron Configuration: _______________________
ms =
Noble gas configuration: ______________________
n=
l=
Na
____ e-
ml =
Electron Config: ____________________________
ms =
Noble gas config: ___________________________
Why don’t the electrons fill the p orbitals by sharing them first? Why do they go to their own orbital?
Think about electrons. What are the charges of electrons? _______________
If you put two electrons near each other, what will they do to each other? _______________
So if you try to put two electrons into an orbital together, they will try to push each other out! And if there is somewhere else for an
electron to go without having to gain energy, that electron will move!
So if there are empty p orbitals, the electrons push each other into the empty ones before they end up sharing! There is a name for
this!
3. ___________________________ rule states that orbitals of equal energy are each occupied by one electron before any orbital is
occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin.
We’re ready to talk about ml now! Quantum number ml tells you which orbital the electron is in!
s
____
p
____
____
____
d
____
____
____
____
____
f
____
____
____
____
____
____
____
Let’s go back and fill in all the ml from above.
n=
l=
S
ml =
ms =
_____ e-
Electron Config:
Noble gas Config:
n=
l=
Cl
ml =
ms =
_____ e-
e- config:
noble gas config:
n=
l=
Sc
ml =
ms =
_____ e-
e- config:
noble gas config:
n=
Ti
l=
ml =
____ e-
ms =
e- config:
noble gas config:
Notice: we always start at 1s every time we fill electrons.
2. The _____________ principle states that an electron will occupy the lowest-energy orbital that can receive it.
Quantum Numbers:
a. The __________________________ quantum number (n), indicates the main energy level. Values of n are positive integers 1, 2, 3,
and so on.
b. The ________________________ _________________________ quantum number (l ) indicates the shape of the orbital.
c. The _________________________ quantum number (ml) indicates the orientation of an orbital around the nucleus. Can have a
value of –
l through zero to + l.
d. The _____________________ quantum number (ms) has only two possible values, + ½ and – ½, because only two electrons can
exist in the same orbital and indicates one of the two fundamental spin states of an electron.
(l)
Orbital Type
0
1
2
3
s
p
d
f
B. Representing Electron Configurations in Orbital Notation
1. The arrangement of electrons in an atom is known as the atom’s _______________________________
______________________________. One type of electron configuration is ______________________
_____________________________ .
Standard Electron Configurations
A.Standard electron configurations eliminate the __________ and ____________ of orbital notation.
1. The number of electrons in a sublevel is shown by adding a _______________.
1s2
Noble Gas Configuration
Unit 3 Page 9
Noble Gas Electron Configurations
A. A ________________ _______ configuration is an electron configuration that utilizes a noble gas which has its
____________ level fully occupied.
[He] = 1s2
[Ne] = 1s22s22p6
[Ar] = 1s22s22p63s23p6
[Kr] = 1s22s22p63s23p64s23d104p6
[Xe] = 1s22s22p63s23p64s23d104p65s24d105p6
[Rn] = 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p6
1. Noble gas configurations are often used to help _____________ the electron configurations of those elements that contain
large numbers of electrons.
Go back in and do the noble gas configurations in the chart above!
And now, let’s do some special exercises.
1.
a. Write the electron and noble gas configurations for Mo WITHOUT doing the orbital notation!
b. Write the quantum numbers for Mo!
2.
What is the noble gas configuration of Ta?
3.
What is the noble gas configuration of Bi?
4.
What element am I talking about?
a. n = 4
b. n = 5
l=3
5.
l=1
c. n = 1
l=2
d. n = 5
l=2
e. n = 3
l=1
ml = -2
ml = 0
ml = 0
ml = -2
ml = +2
ms = -½
ms = +½
ms = -½
ms = -½
ms = +½
How can you tell how many valence electrons are in an element from:
a. The periodic table?
b. An orbital diagram?
c. Electron configuration?
d. Noble gas configuration?
e. Quantum numbers?
Lewis Valence Electron Dot Structures
Unit 3 Page 10
Lewis Valence Electron Dot Structures
A. Lewis _______________ electron dot structures show the symbol of an element and its number of ______________ electrons.
1. ________________ electrons are those electrons in the _________________ energy level of an atom.
2. ________________ electrons are integral in determining how the atom will __________________ react with other atoms.
B. Use the following steps to draw a Lewis valence electron dot structure.
1. Write the element _______________.
2. Determine the __________ number for the element.
a. The ___________ number indicates the number of ______________ electrons.
3. Start on one of your element symbol and, moving clockwise, put a ______ every 90° until the number of valence electrons
present in the atom is achieved.
Go back to your chart from the other day and draw in Lewis Structures next to the orbital diagrams, electron
configurations, etc. Then, if you need more practice, try the ones below.
Element Symbol
C
F
H
Al
Mg
Ne
Group Number
Number of Valence
Electrons
Electromagnetic Radiation
Unit 3 Page 11
Development of a New Atomic Model
A. A new atomic model evolved as a result of the investigation into the absorption and emission of ____________ by matter.
1. Visible ____________ is a kind of __________________________ __________________, which is a form of energy that
exhibits both wave-like and particle-like behaviors as it travels through space.
a. Visible light can behave like a _______ characterized by the measurable properties of ____________ and
______________.
1. _______________ (λ) is the distance between corresponding points on adjacent waves.
2. ________________________ (f) is defined as the number of waves that pass a given point in a specific
time, usually one second (Often measured in hertz, Hz).
3. The wavelength and frequency for light waves can be
related mathematically in the following way:
c= f λ
b. Visible light can behave like a stream of particles or ____________. A ____________ is a particle of
electromagnetic radiation having zero mass and carrying a specific amount of energy.
1. The ________________________ effect is evidence that light behaves as stream as particles.
2. Max Planck suggested and Albert Einstein elaborated on the following formula when describing the
relationship between frequency and the ___________ of energy of a photon.
Ephoton = h f
3. A ________ is a specific amount of energy proportional in size to the frequency of the radiation it
represents.
B. Scientists use this understanding of ____________ to also describe the properties of the _______________ and their behavior in
the electron cloud.
Absorption and Emission Spectra
Unit 3 Page 12
Absorption and Emission of Energy by Electrons
A. Atoms will exist in two states in relation to ___________.
1. The lowest potential energy state of an atom is its ____________ _____________.
2. A state in which an atom has a higher potential energy than it does in its ground state is an __________________
_________________.
B. Electrons can move to a higher energy orbital by gaining a specific amount, or _______________, of __________________.
C. When electrons fall back from the excited state a specific amount or, a ______________ , of _____________ is released equal to
the energy difference between the two orbitals.
D. The ____________________ _________________ of an element is the relative intensity of each frequency of electromagnetic
radiation emitted by the atom as the atom’s electrons return from the excited state to the ground state.
Emission Spectrum of Hydrogen
E. When an electric current is passed through a glass tube that contains hydrogen gas at low pressure the tube gives off blue light.
When this light is passed through a prism (as shown in the figure below), four narrow bands of bright light are observed against a
black background.
Each band is a different color than the other, corresponding with the wavelength and frequency of the light as it fell from an excited
state back to ground state.
The four bands of light will always be the same for hydrogen, 100% of the
time. Meanwhile, all other elements also have their own emission spectra that are
the same for that element all the time.
No two elements will EVER have _____________ emission spectra. This means
that emission spectra can be used to ____________ what kind of element(s)
is/are in a sample!
Unit 3 Appendix—Polyatomic Ions
Unit 3 Pg 13
Recall that a polyatomic ion is a group of elements, usually nonmetals, that are covalently bonded together. Due to unequal sharing of
electrons, the overall group of elements will carry a charge. In most cases, the charges are negative, but sometimes they are
positive.
This year, you will be required to memorize a list of polyatomic ions—both their formulas, and their ions. Each six weeks, there
will be certain ions we memorize. You will be expected to know all old ions from previous six weeks as well as the new ions we
add on each cycle.
For the 2nd six weeks, you STILL need to have all the 1st Six Weeks ions memorized (your “Nick the Camel” ions).
Additionally, you will also need to memorize the following other ions:
Ion Name
Formula
Ion Name
periodate
hypoiodite
perchlorate
hypochlorite
perbromate
hypobromite
Formula
Notice a pattern between the “per-ate”s and “hypo-ite”s of similar ions, especially compared to ions you already know.
For instance, write the formulas of perbromate, bromate, bromite, and hypobromite.
perbromate: ________
bromate: ________
bromite: ________
hypobromite: ________
Compare the above four formulas. What pattern do you see?
I notice that _______________________________________________________________________________________.
This pattern holds true for all of the “per-ates” and “hypo-ites”! So as long as you can use the sentence, you can figure
out these new ions!
Nick the Camel ate an Icky Clam for Supper in Phoenix with his Bros
How does a “per-ate” compare to an “-ate” ion: ___________________________________________________________
How does a “hypo-ite” compare to an “-ite” ion: ___________________________________________________________
A general ranking:
Please note: if you memorize the sentence
wrong, you will not be able to properly
determine the ion formulas! For instance, if you
spell “Phoenix” with the wrong number of
vowels, or if you accidentally memorize it as
“icky clams” instead of “AN icky clam,” or if you
mistake Clam as standing for carbonate when it
actually stands for chlorate.
per________ate:
________ate:
________ite:
hypo________ite:
Unit 3 Appendix—Second Six Weeks Quizzes
Unit 3 Pg 14
In Pre-AP Chemistry, we will take only two quizzes in class every Six Weeks. These two quizzes will both cover the same material as each other.
This material is not necessarily information that we are covering in the current unit. Rather, the materials on the quizzes will be content that the Pre-AP
teachers feel is important for you to know and continue practicing all year long. These quizzes will build on each other as far as what they cover
from one Six Weeks to the next.
We have a system in Pre-AP Chemistry to make retesting easier:


If you pass the first quiz of the six weeks (grade of 70+), great! Just make sure you study and also pass the second quiz.
If you fail the first quiz of the six weeks (grade <70), make sure you study hard for the second quiz!
o
If you pass the second quiz, we will count that as your retest for the failed quiz grade!

So if you get a 30 on the first quiz and a 70 or higher on the second quiz, you will keep your second quiz grade AND your
first quiz grade will go up to a 70!

If you don’t pass the second quiz but score higher than your original score, your first quiz grade will raise to whatever you
got on the second quiz. So if you got a 30 on the first quiz and a 60 on the second quiz, your first grade will still go up to
a 60.
o
If you fail the second quiz, you will have to come in before or after school to take a requiz.

Use the testing schedule on my website (also posted outside my classroom) to know which room to go to and when
(every teacher will have a copy of the requiz for you to take, no matter when you go in)

If you pass the requiz, all failing quiz grades you have will be raised to 70s.

If you fail the requiz, your top 2 out of the 3 grades will go on your report card.

As before, if you fail the requiz but score higher than either of your original quiz grades, your original grades will go up to
whatever you made on the requiz.
Feel free to ask any questions about this system that you may have.
Second Six Weeks Quiz Material that YOU NEED TO STUDY:

Everything from First Six Weeks Quizzes, including but not limited to:
 Sig Fig measurements and calculations
 Be able to look at a number and figure out how many significant figures it has
 Be able to look at a measurement and figure out how many significant figures it should be written with
 Be able to do a calculation and figure out how many significant figures the answer should have, and
round the answer appropriately
 Scientific Notation—Be able to put a number into or out of scientific notation
 Conversions and the Metric System— Be able to convert metric units from one prefix to another, or to a base
unit
 All the First Six Weeks ions (use Nick the Camel to figure out the ions and formulas (including charges) (See Pg 16
of Unit 1—Appendix for Unit 1)

Moles




Convert particles (atoms, molecules, etc.) to moles and/or moles to particles
Convert grams to moles and/or moles to grams
Convert particles to grams and/or grams to particles
NEW Ions (See Unit 2 Appendix—Unit 2-5 Pg 4)—all the per-ates and hypo-ites
Unit 3 Appendix—More Moles Practice
Try these mole problems so you don’t forget how to do them! Moles will be on your quizzes for the rest of the year!
1. Find the number of moles of argon in 452 g of argon.
2. Find the grams in 1.26 x 10-4 mol of C.
3. Find the mass in 2.6 mol of lithium.
4. How many atoms are in 0.750 moles of zinc?
5. How many molecules are in 0.400 moles of N?
6. How many moles are 1.20 x 1025 atoms of phosphorous?
7. Find the mass, in grams, of 1.00 x 1023 molecules of Zr.
8. How many particles are there in 1.43 g of neon?