The Quantum Model of the Atom
Dec 13, 2015
Electrons as Waves• Louis de Broglie (1924)
– Applied wave-particle theory to electrons
– Electrons exhibit wave properties
QUANTIZED WAVELENGTHS
Quantum Mechanics• Heisenberg Uncertainty Principle
– Impossible to know both the velocity and position of an electron at the same time
Quantum Mechanics
σ3/2 Zπ
11s 0
eΨ a
• Schrödinger Wave Equation (1926)
– Finite number of solutions quantized energy levels
– Defines probability of finding an electrons
Quantum Mechanics
Radial Distribution CurveOrbital
• Orbital (“electron cloud”)
– Region in space where there is 90% probability of finding an e-
Electron Structure
• Electrons arranged into energy levels.– Names like “n=1” and “n=2”.
n = 1n = 2n = 3n = 4
Nucleus Mor
e E
nerg
y
Electron Structure
• Energy levels are divided into sublevels.– Sublevels within an energy level have similar
energy.
Electron Structure
• Sublevels are made of orbitals.– Each orbital can hold up to 2 electrons.
Sublevel Orbitals Electrons
S 1 2
P 3 6
D 5 10
F 7 14
Valence Electrons• Valence electrons – Electrons in an atom’s highest-
numbered energy level.• You can tell how many valence electrons any atom should
have by its position in the periodic table.
12 3 4 5 6 7
82
variable
Lewis Dot Diagrams
• Lewis Dot Diagram – shows the valence electrons of an atom.– First 2 electrons paired on one side.– Remaining electrons are placed on other sides.– Should never have more than 8 dots.