# Chapter 5 Chemistry

Chapter 5: Electron Clouds and Probability

## Terms

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If all points of = probability are connected,
some 3-D shape is formed.
As the wavelength of an object increases,
its momentum decreases.
Light
has the properties of both waves and particles
in the 3rd and 4th levels
there is overlapping
in an atom there are many points of
equal probability
f
7 pairs electrons & 7 orbitals
The 3rd quantum # is m -
represents orbitals and indicates their direction in space
orbital
The space that can be occupied by one pair of electrons
vectors have both
magnitude and direction
The more certain we are of the momentum
the less certain we are of position and vice versa.
DeBroglie thought
if Planck were correct then it might be possible for particles to have some of the properties of waves
wave-particle duality of nature
The two-sided nature of waves and particles
Each electron in an atom can be described
as a unique set of four quantum numbers: n, l, m, s
Max Planck
theorized that energy is made up of discrete amounts of energy called quanta. This theory seemed to give waves properties of particles
An electron effectively occupies
all the space around a nucleus.
d
5 pairs electrons & 5 orbitals
sublevel names:
(lowest energy to highest) s, p, d, f
Momentum
is a vector quantity which consists of mass times velocity
Quantum mechanics describes
the behavior of extremely small particles traveling at velocities near that of light
The # of sublevels in an energy level =
the value of n, the principal quantum #.
Heisenberg's Uncertainty Principle
the exact position and momentum of an electron cannot be determined at the same time.
DeBroglie's equation
ʎ=h/mv
s
1 pair electrons & 1 orbital
An energy level is actually made up of
many energy states closely grouped together ( called sublevels )
p
3 pairs electrons & 3 orbitals
The symbol --> above a quantity
means it is a vector quantity
An electron can only occupy specific energy levels when:
1. The energy levels are numbered with positive integers starting with 1, 2. The principal quantum number, n, describes the energy level, 3. The maximum # of electrons in an energy level = 2n^2
Newtonian or classical mechanics describes
the behavior of visible objects traveling at normal velocities
Momentum equation
p = mv
Particles (matter) also have both properties
In large particles we can ignore wave characteristics. In small particles (like electrons) we cannot.
since p = mv
then ʎ= h/p
probability =
# of times in position X/ divided by sum of times in all positions
The position of an electron can best be represented by
a cloud
We cannot observe
both the wave characteristics and particles characteristics of an electron at the same time.
The second quantum number, l
describes sublevels

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