Download Section 11.3 Atomic Orbitals

Section 11.3
Atomic Orbitals
• Georgia Performance
Standards:
– SC3 (b): Use the orbital
configuration of neutral
atoms to explain its effect
on the atom’s chemical
properties.
• Essential Questions:
– How do you describe the
behavior of an electron?
– How does the orbital
configuration of atoms
explain their chemical
properties?
Section 11.3
Atomic Orbitals
Objectives
1. Compare and contrast the Bohr model and the quantum model
of the atom
2. Discuss Louis de Broglie’s role in the development of the
quantum model of the atom
3. Explain how the Heisenberg uncertainty principle and the
Schrodinger wave equation led to the idea of atomic orbitals.
4. To learn about the shapes of the s, p, d and f orbitals
5. To review the energy levels and orbitals of the wave mechanical
model of the atom
6. To learn about electron spin
Section 11.3
Atomic Orbitals
A. The Hydrogen Orbitals
• Orbitals do not have sharp boundaries.
Section 11.3
Atomic Orbitals
A. The Hydrogen Orbitals
Hydrogen Energy Levels
• Hydrogen has discrete energy
levels.
– Called principal energy
levels
– Labeled with whole numbers
Section 11.3
Atomic Orbitals
A. The Hydrogen Orbitals
Hydrogen Energy Levels
• Each principal energy level is divided into sublevels.
– Labeled with numbers and letters
– Indicate the shape of the orbital
Section 11.3
Atomic Orbitals
A. The Hydrogen Orbitals
Hydrogen Energy Levels
• The s and p types of sublevel
Section 11.3
Atomic Orbitals
A. The Hydrogen Orbitals
Hydrogen Orbitals
• Why does an H atom have so many orbitals and only 1
electron?
– An orbital is a potential space for an electron.
– Atoms can have many potential orbitals.
Section 11.3
Atomic Orbitals
The Quantum “Wave” Mechanical Model of the Atom
What’s wrong with the Bohr model?
Section 11.3
Atomic Orbitals
B. The Wave Mechanical Model: Further Development
Atoms Beyond Hydrogen
• The Bohr model was discarded because it does not
apply to all atoms.
• Atoms beyond hydrogen have an equal number of protons
and electrons.
– Need one more property to determine how the electrons
are arranged
– Spin – electron spins like a top
Section 11.3
Atomic Orbitals
Heisenberg, de Broglie, Schrodinger
• Developed a model of the atom based on wave mechanics
(quantum mechanics)
– The electron bound to the nucleus seemed similar to a
standing wave
• De Broglie – originated the idea that the electron also shows
wave properties (in addition to particulate properties)
• Schrodinger – put emphasis on the wave properties of the
electron
Section 11.3
Atomic Orbitals
Standing Waves & Musical Instruments
• A string attached to a violin or guitar vibrates to produce
a musical tone
• The waves are “standing” because they are stationary,
they don’t travel the length of the string
Section 11.3
Atomic Orbitals
•The dots indicate the nodes, or points
of zero lateral (sideway) displacement,
for a given wave.
•There are limitations on the allowed
wavelengths of the standing wave.
•Each end of the string is fixed, so there
is always anode at each end
• There must be a whole number of half
wavelengths in any of the allowed
motions of the string
Section 11.3
Atomic Orbitals
Heisenberg’s Uncertainty Principle
• There is a limitation to just how precisely we can
know both the position and momentum of a
particle at a given time.
• The more accurately we know a particle’s position,
the less accurately we can know its momentum, and
vice versa.
– Limitation is too small for large particles
– Limitation is significant for small particles
Section 11.3
Atomic Orbitals
Heisenberg’s Uncertainty Principle
• Applied to the electron:
– We cannot know the exact motion of the electron
as it moves around the nucleus
– Therefore, it is not appropriate to assume that
the electron is moving around the nucleus in a
well-defined orbit, as in the Bohr model.
Section 11.3
Atomic Orbitals
Quantum Numbers
•Principle Quantum Number (n):
•Angular Momentum Quantum number (l)
•Magnetic Quantum Number (ml)
•Spin Quantum Number (ms)
•(Pauli Exclusion Principle)
Section 11.3
Atomic Orbitals
Quantum Numbers for the First Four Levels of Orbitals
in the Hydrogen Atom
Section 11.3
Atomic Orbitals
Orbital Shapes and Energies
Section 11.3
Atomic Orbitals
1s Orbital
Section 11.3
Atomic Orbitals
2px Orbital
Section 11.3
Atomic Orbitals
2py Orbital
Section 11.3
Atomic Orbitals
2pz Orbital
Section 11.3
The
Boundary
Surface Representations of All Three 2p Orbitals
Atomic
Orbitals
Section 11.3
Atomic Orbitals
Orbital
3d x2  y 2
Section 11.3
Atomic Orbitals
3dxy Orbital
Section 11.3
Atomic Orbitals
3dxz Orbital
Section 11.3
Atomic Orbitals
3dyz Orbital
Section 11.3
Atomic Orbitals
Orbital
3d z 2
Section 11.3
The
Atomic
Boundary
Orbitals
Surfaces of All of the 3d Orbitals
Section 11.3
Representation of the 4f Orbitals in Terms of Their
Atomic Orbitals
Boundary Surfaces
Section 11.3
Atomic Orbitals
B. The Wave Mechanical Model: Further Development
Atoms Beyond Hydrogen
• Pauli Exclusion Principle - No 2electrons in the same atom can have
the same set of 4 quantum numbers. An atomic orbital can hold a
maximum of 2 electrons and those 2 electrons must have opposite spins
• Hund’s Rule – every orbital in a subshell is singly occupied with one
electron before any one orbital is doubly occupied, and all electrons in
singly occupied orbitals have the same spin.
• Aufbau’s Principal – An electron occupies the lowest energy orbital that
can receive it, then it will go back and pair up.