Chemistry Ch. 4 Notes (pg. # 1)
- Electrons are located in e_________ c_________.
Question: Do we __________ anything about electron clouds?
Answer: ________
Question: How do we know anything about electron clouds?
Answer: L_______ !!
Light:
- When we refer to “light”, we are referring to the entire
e__________ s__________.
o This includes not only visible light, but also radio
waves, microwaves, i________ , u________,
x______, g______ rays.
- Light travels as an electromagnetic ________.
o All waves have a w_________ (which is commonly
measured in ______ or ________) and a f_________
(which is frequently measured in ________)
- The speed of light is c________, and has a value of
________ meters/second.
Equation for the speed of light:
c=
- Our eyes detect differences in color by detecting
differences in ___________.
o Ex. Blue light has a wavelength of ______ nm
o Ex. Red light has a wavelength of ______ nm
- Because the speed of light is constant, if we are given the
wavelength, we can calculate the _________, and vice
versa.
Ex. Calculate the frequency of light that has a wavelength of
2.00 X 10-8 meters.
Ex. Calculate the wavelength of light that has a frequency of
4.0 X 1014 Hz.
Photons:
- Light is thought to not only travel in waves, but also to
consist of tiny “packets” of energy called ________.
- The amount of energy in a photon can be calculated using the
following equation:
Ep = h (_________)
h is a constant and
has a value of
6.626 X 10-34 J s
Ex. Calculate the amount of energy that photon of light has whose
frequency is 5.0 X 1014 Hz.
Multiplying and Dividing in Scientific Notation:
1.) When multiplying, multiply the digits and _____ the exponents.
ex. (2.0 X 107) ( 3.0 X 106) =
2.) When dividing, divide the digits and ________ the exponents.
ex. 9.0 X 1010
3.0 X 107
Other Examples:
1.)
(1.7 X 103) (3.1 X 104)
2.)
8.4 X 109
2.1 X 1019
3.)
(5.745 X 108) (9.70 X 1015)
4.)
8.4 X 1010
19.1 X 10-7
Chemistry Ch. 4 Notes (pg. # 2)
Making the Connections Between Light and E__________:
- When we place a copper-containing compound in a flame, we
observe a ________ color.
o This light has a __________ of approximately 450nm,
or 4.5 X 10-7 m.
 The ____________ of this light would be
6.7 X 1014 Hz.
 One photon of this light would have an
_________ of 4.4 X 10-19 J.
o It is because of the changes in energy of the
_________ that results in the release of a
_________.
Diagram:
In Conclusion: There must be an energy transition of
e_________ in the copper atom of 4.4 X 10-19 J. Therefore we know
something about the energy l________ of the electrons in a Cu atom.
Now we are on our way…
Atomic Spectra:
- We can measure the specific wavelengths given off by an
atom by using a s_____________.
o From here, we can determine all sorts of energy levels
in the atom.
o Atomic Spectra are also used to identify elements
present in the s____ and other s______.
Chemistry Ch. 4 Notes (pg. # 3)
- As stated earlier, by measuring wavelength and calculating
the energy of photons, we are able to determine the energy
l_________ in a particular element’s atoms.
o It turns out that the configuration of the electrons is
still more c____________ than simply knowing energy
levels.
 The breakthrough came when scientists proposed
that the electron, like light, behaves not only like
a particle, but also like a _______.
 This led to wave mechanics, which is now called
q_________ m_________.
 Q_________ m__________ is able to
completely describe the electrons in an
atom.
Electron Configurations:
- According to quantum mechanics, each electron has
____ quantum _________ assigned to it in an atom.
o These numbers describe the energy, sh______
of the electron o_______, and s______ of the
electron.
o For an entire atom, we can get the entire
e_________ c__________ which is based on
the four quantum numbers.
The four quantum numbers:
1.)
is the p________ energy level.
“n”
: n
Analogy: It is like the f_______ in a school building.
- n has values of 1, 2, 3, …
2.)
“tells us the type, or the s_______ of the
electron orbital.
“l”
: “l
- “l” has values of 0, 1, 2, or 3, but we usually refer to them
instead as _____, _____, _____, and ____.
Analogy: “l” is like the c_________ on a particular floor.
3.)
ml
specifies in w_______ “l” orbital the electron is
located.
: ml
Analogy: It is like specifying at which _______ a
student is sitting.
4.)
tells of the electron’s s______.
ms
:
ms
Analogy: It is like specifying in which c_______ a student is
sitting at the particular table.
Example Electron Configuration:
Magnesium has ____ electrons :
1 s2 2s2 2p6
Chemistry Ch. 4 Notes (pg. # 4)
3s2
Shapes of Orbitals:
- S orbitals (There is ______ s orbital in each principal energy
level.)
o An s orbital has a _________ shape.
1s
2s
3s
- P orbitals: (There are _______ p orbitals in each principle energy
level.)
o A p orbital has a ______________ like shape.
- __ and ___ orbitals: These orbitals are similar in shape to the p
orbitals, however:
 There are _____ d orbitals in every principle energy
level.
 There are _____ f orbitals in every principle energy
level.
Electron Configurations (ground state)
- Orbitals have different ___________.
o Ex. A 1s orbital has a _________ energy than a 3s orbital,
and a 3s orbital has a _________ energy than a 3d orbital.
- Electrons fill the lowest available energy state (orbital).
o Ex. A 1s orbital will be filled before a 2s orbital has any
electrons.
An example of a ground state electron configuration:
Nitrogen:
1s22s22p3
Principal energy level
number of electrons in that orbital
sublevel (type of orbital)
Scheme for determining the orbitals in order of increasing energy:
1
2
3
4
5
6
7
Ex. Write the ground state electron configuration for:
Cl
Na
Al
Fe
Ne
Chemistry Ch. 4 Notes (pg. # 5)
- It is possible to use the ________ __________ to determine
the order of orbital energies.
To Illustrate and b_______ the idea:
- Find the electron configuration for:
H
He
Li
Be
- We notice that every element has the s_______ electron
configuration as the element before it, p______ one electron.
- Fine the electron configuration for:
B
C
F
Ne
N
O
Sc
- We notice that elements in the same “b_______” on the periodic
table end with the same type of orbital.
o Example:
H, Li, Be, are in the ____ block
B, C, N, O, F, Ne are in the ____ block
Sc is in the ___ block
Ex. Determine the last “term” of the electron configuration for each
of the following elements:
Cr
Mn
Rb
Sr
La
Sn
Xe
Si
S
P
Br
- Finally, since we can determine the ending “term” in the electron
configuration from looking at the periodic table, and since each
element has the same configuration as the previous element (plus
one electron), we can use the periodic table to determine the
order of orbital energies.
Chemistry Ch. 4 Notes (pg. # 6)
Abbreviated Electron Configurations (Noble Gas Configuration)
The electron configuration for Ne:
1s22s22p6
For Mg:
1s22s22p63s2
So: We can write the abbreviated electron configuration for Mg as :
[
] 3s2
Ex. The electron configuration for Argon is:
For Manganese:
So: We can write the abbreviated electron configuration for Mn as:
- In order to write the abbreviated electron configuration, you
always use the closest p__________ n_______ g_______.
o What is shown, therefore, are the r_________ electrons.
(Noble gases are un-___________, and therefore their
electron configuration shows all un-reactive electrons.)
Ex. Write the abbreviated electron configuration for:
P
-
Fe
-
S
-
K
-
O
-
- Na
Electron Configurations for I
Ex. Mg
Mg2+
Ex.
F-
F
U
:
- For a monatomic ion, electrons are ________ to or _______
from sublevels in the highest _________ energy level.
Ex. Ca
Ca2+
Ex.
K
K+
Ex.
O
O2-
Ex.
Mn
Mn2+