Download Part 3: Quantum numbers and orbitals

5.2 QUANTUM THEORY AND THE ATOM
PART THREE
Quantum numbers and orbitals
Review: in Bohr’s atomic model, electrons orbited the
nucleus as shown below. To mathematically describe
the orbit of an electron, Bohr used one quantum
number, n = 1, 2, 3 ……which designated 2 things:
The orbit for n = 1 is
CLOSEST TO
MOST FAR FROM
the nucleus, and is
HIGHEST
LOWEST
in energy
Bohr’s orbits were all
_____________________
in shape.
In quantum theory, electrons may be
found in atomic orbitals.
The book says an orbital is:
“a 3-D region around the nucleus that describes
the probable location of an electron.”
in other words:
each orbital can contain ____, ____, or ____
electrons (how many?)
Quantum mechanics has ______________
quantum numbers to describe the
arrangement of electrons. The first
quantum number is known as the
and is very similar to Bohr’s. It is
n = 1, 2, 3 ……
and describes roughly the same things as
Bohr’s quantum number, n.
In quantum mechanics, the principal, the
second, and the third quantum numbers
together describe the
of an electron; i.e., the area of space that the
electron has a________% probability of being
found in;
The fourth quantum number describes a
particular electron in that orbital (actually the
spin of the electron.)
QUANTUM
#
Principal:
quantum #
n = 1, 2, 3….
Second
quantum #
Third
Quantum
#
SPECIFIES
DESCRIBES FOR AN
ORBITAL…
Bohr’s orbits were all _____________ in shape.
In quantum mechanics, each orbital has one of
______________ different possible shapes.
A sublevel contains ______________________
orbitals, depending on the shape of the orbitals
All of the orbitals in a particular sublevel have
THE SAME
DIFFERENT
shape(s)
s orbitals are shaped like a sphere.
How many orbitals can there be in
one s-sublevel?
p orbitals are shaped like a figure-8.
There are 3 in any one p-sublevel.
Each one has a different orientation
in space
d-orbitals are mostly shaped like 2
figure-8’s together. There are 5 of
them in any one d-sublevel.
Here are f orbitals. Any one sublevel
can contain 7 f orbitals
The orbitals have differing amounts of energy.
For orbitals in the same principle energy level:
s<p<d<f
Look at the shapes – does this make sense?
The Aufbau Principle
states that:
each electron occupies
the lowest energy
orbital available.
Does this make sense?
With this basic knowledge of quantum numbers and
orbitals, we can now begin to develop a picture of the
atom and to write electron configurations; this is a
very important skill in chemistry. Based on the
electron configuration of each element, we can explain
and predict the behavior of that element.