Chemistry I Chapter 4 Outline
ARRANGEMENT OF ELECTRONS IN ATOMS
The emission of light is fundamentally related to the behavior of electrons.
For graded assessments, you will need to be familiar with the following
terms: electromagnetic radiation, electromagnetic spectrum, wavelength (λ),
frequency (ν), photoelectric effect, quantum, photon, ground state, excited state,
emission-line spectrum, continuous line spectrum, Heisenberg uncertainty
principle, quantum theory, orbital, quantum numbers, principal quantum number
(n), angular momentum (l), magnetic quantum number (m), spin quantum
number (+1/2, -1/2), electron configuration, Aufbau principle, Pauli exclusion
principle, Hund’s rule, noble gases, noble-gas configuration
I. THE DEVELOPMENT OF A NEW ATOMIC MODEL
A. In the early twentieth century, a new atomic model evolved as a result
of investigating what? ________________________________________
Scientists would go on to discover that light behaved as both a __________ and
a _____________. List 4 types of electromagnetic radiation that is discussed by
the textbook _______________________________________. What is the value
given to the speed of light constant? Do not forget units__________________.
Wavelength can be expressed in ___________, ___________ or ____________. What equation
relates the speed of light constant to wavelength and frequency? ____________________
What are the units for each of the components of the aforementioned equation?
c _______________; λ _________; ν________.
B. Max Planck described the behavior of light as being particle-like by
using the definition of the _______________________. What is a quantum?
______________________________________________. What relationship
(equation) did Planck propose to describe energy, E; frequency, ν; and h,
Planck’s constant? _________________ What is the value of Planck’s constant?
_______________________ (don’t forget units) What units are used to measure
energy? _________ frequency? __________ What is a photon?
__________________________________________ What other notable scientist
expanded on the particle-like nature of electromagnetic radiation? (pg 100)
_______________ This scientist theorized that there was a required minimum
amount of energy a photon must possess in order to excite an electron to a
higher energy state. What happens if the photon does not possess this
minimum required energy? __________________________________________
C. What happens to the potential energy of gas atoms when current
(electricity) is passed through it at low pressure? ________________________
Is there only one excited state an atom can have? __________ Is there only
one ground state an atom can have? __________ What occurs when the
electron of an atom goes from an excited state to a lower excited state or to its
ground state? ___________________________________ Give an example of
this phenomenon that is quite familiar in our culture (pg 100, figure 4)
__________________. The emission line spectrum shows scientists the specific
energy levels that exist in each individual atom of an element. In fact, chemists,
to identify an unknown substance, regularly exploit this phenomenon. Electrons
are excited by either increased energy from a flame or from a current of
electricity and then as the electrons fall back to their ground states, they emit
specific magnitudes of energy that also correspond to a particular frequency and
wavelength of electromagnetic radiation.
D. So far we have discussed several atomic theorists that you will need to
know for your up-coming examinations: Dalton, Thomson and Rutherford. Make
sure you are familiar with these scientists’ contribution to chemistry. Niels Bohr
is the fourth theorists that is important to the modern model of the atom. He used
_______________________ to link electrons to photon emission. According to
his model (and the current atomic model), the electron can circle the nucleus only
in allowed paths which are called _________. Therefore they also have a fixed
________________. When an atom is in its lowest state, in terms of distance
from the nucleus, where are electrons located? _________________________
When electrons are in excited states, they are located where in terms of distance
from the nucleus? _____________________________ When electrons fall from
a higher energy state to a lower energy state, a photon is given off. This process
is called ______________. When an electron is promoted to a higher energy
state, _____________ is required and this process is called ________________.
Refer to page 102, figure 8 that gives an example of absorption and emission.
Be familiar with this illustration for graded assessments.
(STANDARD CLE 3221.1.3, CLE 3221.1.1, CLE 3221.2.2)
II. THE QUANTUM MODEL OF THE ATOM
A. The scientist _______________ described the wave-particle behavior
of electrons by comparing its behavior to that of light. The scientist
_______________ stated that it would be impossible to know the position and
the velocity of an electron. This principle is known as the
_____________________________________. The two scientists that found
that electrons do not travel around the nucleus in neat orbits but that they exist in
certain three dimensional regions were ______________&______________.
B. The principle quantum number, abbreviated _____, indicates an
electron’s energy and it’s average distance from ________________. More than
one electron can have the same ___________. If they have the same n value,
they are said to be in the same _____________________. Which quantum
number is abbreviated l? __________________________ The values of l
allowed are 0 and all positive integers less than or equal to ________________.
Designation of l=0 corresponds to the subshell _____, l=1 corresponds to the
subshell ______, l=2 corresponds to the subshell _______, and l=3 corresponds
to the subshell _______. Which orbital is spherical? _______ Which orbital is
dumbbell shaped? _______ The d and p orbitals can have several variations to
their shapes. Be familiar with each of these shapes: px, py, pz, dx2 – y2, dxy, dyz,
dxz, dz2 listed on pages 108 and 109 figures 13 - 15. These diagrams indicate the
possible electron clouds around an atomic nucleus. The magnetic quantum
number indicates the various orientations electron clouds can exist around an
atomic nucleus. The magnetic quantum number is abbreviated _______. Values
of m are whole numbers, including zero, from –l to +l. The spin quantum number
indicates ___________________________. The spin states of electrons create
a magnetic field meaning that if there are two electrons in an orbital subshell,
they must have opposite spins to decrease their potential energy. The spin
quantum number is indicated by _____________________.
QUANTUM NUMBER
DESIGNATION
DETERMINING VALUES
n
Principle energy level
Periodic table
l
s=0, p=1, d=2, f=3
n-1
s=0;
p= -1, 0, +1;
d= -2, -1, 0, +1, +2;
f= -3, -2, -1, 0, +1, +2, +3
Use molecular orbital notation to
determine the m quantum number –
the magnetic momentum
m
-1/2, +1/2

-1/2;  +1/2
Use molecular orbital notation to
determine the spin quantum number
(STANDARD CLE 3221.1.3, CLE 3221.1.1, CLE 3221.2.2, CLE 3221.Math.2))
III. ELECTRON CONFIGURATIONS
A. Why does the quantum model of the atom improve upon the Bohr model?
________________________________________. Electrons in atoms tend to assume
arrangements that have the ____________________________. The lowest energy
arrangement of an electrons for each element is called the element’s
____________________________________. There are three basic rules to understanding the
modern atomic model that apply to electron configuration. The first rule introduced
by your text book is the Aufbau principle. This principle states that
_______________________________________________________________________________________________.
This principle of electron configuration is also known as the “building up” principle.
Take note of figure 16 on page 111 in your text. This shows the order of increasing
energy for atomic sublevels and each individual box represents an orbital. Note that
the 4s sublevel is ________________ in energy than the _________sublevel. The second rule
for understanding electron configuration is the Pauli exclusion principle. This states
two things; one, that
_________________________________________________________________________________________________
and that _____________________________________________________. The third rule for
understanding electron configuration is Hund’s rule which states that
_________________________________________________________________________________________________
This means that for each orbital, electrons enter these orbitals one at a time to
create the least amount of energy while orbiting an atomic nucleus.
B. How many methods are used to indicate electron configuration? __________
In orbital notation, what represents an unoccupied orbital? ____________________ Show
how an orbital with one electron is represented _______________. Show how an orbital
with two electrons is represented_________________. Note that with two electrons in
one orbital, the electrons have opposite spins. Why?
______________________________________________________________________________________________
When using electron-configuration notation, the number of electrons in a sublevel is
shown by adding ___________________to the sublevel designation. Review and work
through sample problem A on page 113 for an understanding of orbital notation.
Atoms of the elements H and He have what type of orbital orientation considering
that they are 1s1 and 1s2? __________________________________________
C. The _______________________________________________________ is the electroncontaining main energy level with the highest principle quantum number.
Understand tables 3 and 4 on pages 116 and 117 for comprehension of electron
configurations about an atomic nucleus. What is noble-gas notation?
____________________________________________________________________________________________
Elements of the 4th period and beyond have a tendency to defy the usual rules of
orbital configuration because they have so many electrons. Refer to page 111, figure
16 to conceptualize the reason behind this phenomenon. To understand noble-gas
notation, review table 5 on page 118. Sample problem B on page 120 gives an
example of how to show ground-state configuration for an atom of Fe and the
orbital notation for an atom of Fe. Be familiar with how to answer both of these
questions. You are presented with a question and the answer and rationales. YOU
are responsible for working through these objectives and if you have questions, I
encourage you to ask me, your teacher.
(STANDARD CLE 3221.1.3, CLE 3221.1.1, CLE 3221.2.2)