ATOMIC ORBITALS AND ELECTRON CONFIGURATIONS
Waves
Electrons behave like waves. The distance between corresponding points on
adjacent waves is the wavelength (). The number of waves passing a given point per unit of
time is the frequency ().
Waves
The number of waves passing a given point per unit of time is the frequency ().
The Nature of Energy
Max Planck explained it by assuming that energy comes in packets called quanta.
Quantum of energy is the amount of energy required to move an electron from one energy level to another energy level.
Moving to an Excited State
Ground Ground statestate
Excited Excited statestate
Incoming EnergyIncoming Energy
Outgoing EnergyOutgoing EnergyGround Ground
statestateExcited Excited statestate
Electron Energy
The electrons with the lowest energy are located nearest the nucleus.
Ground state electrons- electrons with their normal amount of energy for that energy level.
Excited state electrons- electrons that have absorbed energy and moved to a higher energy level farther from the nucleus.
Atomic Emission Spectrum
When atoms electrons lose energy they emit light
Each atom has a specific light pattern it gives off known as atomic emission spectrum.
More colors were seen than could be explained by Bohr’s Model.
Quantum Mechanics
Erwin Schrödinger developed a mathematical treatment into which both the wave and particle nature of matter could be incorporated.
It is known as quantum mechanics.
Heisenberg Uncertainty Principle: you can never know the speed and location of an electron simultaneously.
ENERGY LEVELS
Each row on the periodic table is a different principle energy level
Row 1 would be level 1 Row 2 would be level 2 and so on. Energy levels can be broken down into
sublevels, or different shaped orbital's.
ATOMIC ORBITALS
A region of space in which there is a high probability of finding an electron
4 different types of sub-levels S P D F
Sub-level S
Spherical Shape Sublevel s has 1 orbital Holds 2 electrons
Sub-Level P
Dumbbell Shaped has 3 orbital's Holds 6 electrons
Sub Level D
Clover Shaped has 5 orbital's Holds 10 electrons
Sub-Level F
7 orbital's Hold 14 electrons
ORBITAL DIAGRAMS
Orbital's will be shown as boxes Electrons will be shown as arrows Each orbital (box) can hold two electrons
(arrows)
Aufbau Principle- Electrons occupy the orbital's of lowest
energy first. Fill from bottom to top. Fill each set of orbital's before moving to a higher
orbital
Pauli Exclusion Principle-Two electrons in the same orbital
must have opposite spins
+
NN
NNSS
SS
-
The magnetic field effects of paired electrons help keep them in the same orbital.
Hund’s RuleElectrons occupy orbital's of the
same energy in a way that makes the number of electrons with the same spin direction as large as possible.
ORBITAL DIAGRAMS
1. Find the total number of electrons from the periodic table
2. Fill each orbital in the orbital filling diagram according to the three principals.
1. Fill from bottom to top2. Two electrons in the same orbital must have
opposite spins3. Pair electrons in the same orbital only when
there is no other option* Each orbital (box) can hold two electrons (arrows)
1s
2s
2p
3s
3p
3d
4s
4p
5s
Element: Lithium
1s
2s
2p
3s
3p
3d
4s
4p
5s
Element: Oxygen Atomic Number 8
1s
2s
2p
3s
3p
3d
4s
4p
5s
Element: Chlorine Atomic Number 17
1s
2s
2p
3s
3p
3d
4s
4p
5s
Element: Strontium Atomic Number 38
WRITING ELECTRON CONFIGURATIONS FROM ORBITAL DIAGRAMS Write the energy level and the symbol for
every sublevel occupied by an electron. Indicate the number of electrons occupying
that sublevel with a superscript.
1s1
Write each orbital in the same order that you filled in using the orbital filling diagram
1s
Writing the Condensed method for electron configuration
Condensed method is a short hand way to write electron configurations.
Consists of electron configuration of the valence electrons and the symbol of the noble gas from the previous period in brackets.
Condensed Method
1s2 2s2 2p6 3s2 3p3
1s2 2s2 2p6 3s2 3p6 4s2 3d6
[Ne] 3s2 3p3
[Ar] 4s2 3d6
Periodic Table
We fill orbitals in increasing order of energy.
Different blocks on the periodic table, then correspond to different types of orbitals.
Some Anomalies
Some irregularities occur when there are enough electrons to half-fill s and d orbitals on a given row.
Some Anomalies
For instance, the electron configuration for copper is
[Ar] 4s1 3d5
rather than the expected
[Ar] 4s2 3d4.