Download II. Units of Measurement

Quantum Theory
Suggested Reading
Pages 104 - 110
I
II
III
Section 4-2
Quantum Theory
 Came about because classical
physics couldn’t explain
everything.
 Why does a metal emit invisible
radiation first (IR – heat) and then
glow red, and then yellow, and
then white?
Quantum Mechanics
Heisenberg’s Uncertainty Principle
There is a limit
to just how
precisely we can
know both the
position and
velocity of a
particle at a
given time.
de Broglie – electrons have wave-like properties.
 Diffraction: The bending of a wave as it passes by
the edge of an object or through a small opening.
Interference: occurs when waves overlap.
Atomic Orbital's
(electron clouds)
 Regions around the nucleus of an
atom where an electron with a
given energy is likely to be found.
Quantum Numbers
 Describe orbital's and electrons in them
 1st Quantum # = main energy level (n)
 2nd Quantum # = shape (l)
 3rd Quantum # = which way it’s pointing(m l )
 4th Quantum # = which way it’s spinning(ms)
principal quantum number
“n”
 Main Energy Level
 Higher “n” = more energy = farther
from nucleus
Angular momentum
quantum number “ l”
 Has to be lower than 1st quantum #
 Indicates shape
 l = 0 s shaped contains 1 orbit
l=1
p shaped contains 3 orbits
 l = 2 d shaped contains 5 orbits
 l = 3 f shaped contains 7 orbits
Shapes of Orbitals
 s orbitals
Shapes of Orbitals
 p orbitals
Shapes of Orbitals
 d orbitals
Shapes of Orbitals
 f orbitals
Magnetic quantum number
“m
”
l
 Tells which
way it’s
pointed
Possible Values of ml
s = 0
 p = -1, 0, +1
 d = -2, -1, 0, +1, +2
 f = -3, -2, -1, 0, +1, +2, +3
Spin quantum numbers ms
 Represented with up
or down arrow
 Can only be +½
(pointed up) or -½
(pointed down)
Pauli exclusion principle
 The rule states that no two
electrons may ever have the same
four quantum numbers.
4 Minute Review