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★ What did the Quantum Mechanical Model tell us about the behavior of electrons?
The quantum mechanical model took Bohr's model, which was limited to smaller elements containing only a single electron, and apply the Uncertainty Principle (the idea that the location and energy of the electron can never be determined) as well as the concept of Wave-Particle Duality to create Quantum Theory.
Quantum Theory - describes mathematically the wave properties of electrons.
Electrons are particles that travel through space as a wave.
Based on Heisenberg's Uncertainty Principle, Schrodinger's wave equations determine only the probability of finding an electron at a given place around the nucleus.
We know that electrons exist as particles, that behave like waves. We also know that we can only determine the probability of the location of the electrons, but not the exact location. This led to the concepts of orbitals.
An orbital is a three-dimensional region around the nucleus that indicates the probable location of an electron.
Orbital Notation
★ Learning Target - be able to write orbital notation for any element.
There are 7 Principle Energy Levels (shells) that increase as they move from the nucleus.
There are 4 Sub-levels (sub-shells) labeled s, p, d, f. These sub-shells each have different shapes because they each have different probabilities for the location of their electrons.
Each sub-level has as particularly shaped orbital.
S sub-level = circular shaped, 1 orbital, max of 2 electrons
p sub-level = dumbbell shaped, 3 orbitals, max of 6 electrons
d sub-level = 4 clover shaped, 1 donut shape; 5 orbitals, max of 10 electrons.
f sub-level = 7 orbitals, max of 14 electrons.
There can only be 2 electrons in each orbital!
The arrangement of electrons in the atom is know as the Electron Configuration. This configuration is governed by three rules.
Aufbua Principle
Aufbua Principle
Electrons occupy positions of the lowest energy.
Electrons are added one at a time to the lowest energy orbital available until all of the electrons of the atom have been accounted for.
Pauli Exclusion Principle
Pauli Exclusion Principle
No two electrons are alike. Two electrons in the same orbital must have opposite spins.
The opposite spins of the electrons forms a magnetic field within the orbital.
Each orbital can hold TWO electrons with opposite spins. These are represented with an up arrow and a down arrow.
Hund's Rule
Hund's Rule
Electrons in the same sublevel occupy empty orbitals first before pairing up. And, unpaired electrons have the same spin.
Summarizing the Rules of Orbital Notation.
Examples of how to write orbital notation for oxygen, flourine and neon.
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