Quantum Model of the Atom – Chapter 4 Notes:
What is a Quantum?
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Electrons are found in
.
When electrons get
, they can
from one energy
level to another.
An electron that has jumped to a new energy level is in an
.
The electron in its original position its in the
.
A
is the amount of
it takes to jump from one energy
level to another.
When an electron is excited, it gives off a burst of
,
called a
.
Different
give off different
of light.
The Quantum Mechanical Model
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The
was created in the 1920s.
This model is very similar to
.
But, electrons don’t orbit the nucleus is neat paths. They are actually found in fuzzy
cloud-like regions called
.
This model states that it is impossible to know the
of
an electron.
It just illustrates places where electrons are
.
Where the cloud appears
, the probability of finding an electron is
.
Where there is
, the probability of finding an electron
is
.
These clouds are called
.
Atomic Orbitals:
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An orbital is a
area around the
of an atom
where you are likely to find
.
There are four types of orbitals:
.
The s-sublevel contains
s-orbital. It can hold
electrons and is
shaped like a
.
The p-sublevel contains
p-orbitals. It can hold
electrons and is
shaped like a
.
The d-sublevel contains
d-orbitals. Most are shaped like a
with
4 petals. The d-sublevel can hold
electrons.
There are
types of f-orbitals. The f-sublevel can hold
electrons.
Draw an s-orbital:
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Draw a p-orbital:
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Draw a d-orbital:
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Quantum Numbers:
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1.
2.
3.
4.
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There are four quantum numbers:
quantum number
quantum number
quantum number
quantum number
Each number indicates a certain
about electrons.
Principal Quantum number – tells what
the electron is in.
Angular momentum quantum number indicates what
the
electron is in (
).
Magnetic quantum number indicates the way the orbital is
.
Spin quantum number describes which direction the electron is
.
Principal Quantum Number:
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Symbolized by the letter “
”
Indicates what
an electron is in.
When the electron is the first energy level, you would write n =
For an electron in the second energy level, n =
.
An electron is in the 4th energy level. What is the value of n?
For a particular electron n = 3. What energy level is it in?
.
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The 1st energy level can hold
electrons. This energy level only contains an
. There are no
-orbitals in the first
energy level.
The 2nd energy level can hold
electrons total. It has an
-orbital and
a
-orbital.
rd
The 3 energy level can hold
electrons. It has
-orbitals.
th
The 4 energy level can hold
electrons. It has
-orbitals.
This number is usually combined with the orbital letter, like 2p or 4s.
Angular Momentum Quantum Number
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Symbolized by the letter “___”
Indicates the _________ of the orbital.
Recall that type of orbital has a different shape.
Value of L
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Orbital
Shape
If L = 1, what type of orbital is the electron in? _________________
What would be the value of L for an electron in an f-orbital? ____________
For a particular electron L = 2. Draw the shape of that orbital below.
Magnetic Quantum Number
 Symbolized by the letter _______.
 Indicates the _________________ of the orbital around the _____________.
 Recall that there are three different p-orbitals. Each of these orbitals has a figure-eight
shape. But, each is turned differently with respect to the nucleus. One is
_________________, one ____________, and the other is ______________
_______________.
 The magnetic quantum number is used to describe what ______________ the orbital is in.
 There is only one type of ___orbital. So, there is only _______ possible value of m. For
the s-orbital, m is always equal to ________.
 For the p-orbital, there are _________ possible values of m. For a p-orbital, m can equal _________________.
 The d-orbital has ________different values of m.
 The f-orbital has ________ possible values of m.
Type of Orbital
Possible Values of “m”
Spin Quantum Number
Symbolized by the letter “___.”
Electrons __________ on an _________, the same way the Earth does.
Electrons can spin
or
.
The spin quantum number indicates which
the electron is
________________ in.
 For any electron, the spin quantum # has two possible values: ________________.
 If the electron is spinning in a
direction, spin =
 If the electron is spinning
, spin =
.
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An orbital can only hold _________ electrons.
These electrons must have ____________________ ______________.
This means for one of these electrons s= ½ and for the other s= - ½
When electrons are paired in an orbital, they must have different spins.
This means for one of these electrons s= ½ and for the other s= - ½
Electron Configurations:
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There are three rules that guide how electron configurations are written:
1. Aufbau Principle - states that electrons are placed in orbitals one electron at a
time AND that you always place electrons in the lowest energy orbital. That
means start with the first energy level and work your way up.
2. Pauli-Exclusion principle – States that no two electrons can have the same set of
quantum numbers. This means that electrons are sometimes paired together in
orbitals, but they aren’t moving the same way. One electron is spinning counterclockwise and one is clockwise.
3. Hund’s Rule – states that when multiple orbitals are available (like in the p, d, or f
sublevel), put one electron in each energy level first. Then pair electrons up.