Download Lesson 2 - The Bohr and Quantum Mechanical Model of the Atom

Lesson 2 ­ The Bohr and Quantum Mechanical Model of the Atom
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Bohr's Model of the Atom (3.2)
What is a quantum of energy?
A unit of energy (package of energy)
Analogy: money ($) comes in "quanta" of 5¢, 10¢, ...
energy from photons of light or electron transitions are quantized
Lesson 2 ­ The Bohr and Quantum Mechanical Model of the Atom
October 03, 2014
Atomic Spectra (see page 144)
When electromagnetic radiation (light) is passed through a spectrometer...
White light Emission Spectrum
Continuous Spectrum
Line Spectrum
Bohr Atom ­ Interactive
Bohr Model of a Hydrogen Atom
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1p+
0n0
Energy level
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4
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Electrons exists in certain energy levels. Lesson 2 ­ The Bohr and Quantum Mechanical Model of the Atom
Bohr's model explains well:
• how electrons occupy energy levels • maximum number of electrons at each level
Bohr's model does not account for:
• energy levels in atoms with more than one electron
• how electrons are found around the nucleus
The Classical Model Ends
Moving Toward a Quantum Mechanical Model (3.3)
deBroglie:
Electrons exhibit behaviour of particles AND waves
Video: Particles and Waves ­ The Mystery of Quantum Mechanics
October 03, 2014
Lesson 2 ­ The Bohr and Quantum Mechanical Model of the Atom
October 03, 2014
The Quantum Mechanical Model
Schrodinger: Energy of an electron can be represented by a wave function
1. Electrons can exist in different orbitals by absorbing or emitting quanta of energy
2. The location of electrons is given by a probability distribution
According to Heisenberg's Uncertainty Principle, it is impossible to know the exact position and velocity of an electron. The orbitals of electrons are determined statistically by creating a 3D electron probability density. Video: The Uncertain Location of Electrons
Video: What is the Heisenberg Uncertainty Principle?
Lesson 2 ­ The Bohr and Quantum Mechanical Model of the Atom
October 03, 2014
Models of a hydrogen atom