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Ann Verner

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Unit 7
- Quantum mechanical theory of the atom
- Model that explains how electrons exist in atoms
- Nature of Light
- Wave particle theory
- Electromagnetic Radiation (EMR)
- Energy from oscillating electric and magnetic field
- Wave composed of oscillating mutually perpendicular electric and magnetic
fields propagating through space (page. 278)
- 
- Electric field- region of space where electrically charged particles experience
a force (2 protons together feel a force when close together)
- Magnetic field, region of space where magnetic particles experience a force
(2 magnets brought together will feel a force)
- characterize waves by amplitude (vertical height/crest) and wavelength (distance
between adjacent crest), both are related to quantity of energy carried by wave, frequency
(number of cycles that pass through a stationary point in a given time, Hz (1 cycle/s))
- Longest wavelength (750 nm, Red), shortest wavelength (400 nm, violet)
- Electromagnetic Spectrum
- Index of all wavelengths of electromagnetic radiation

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- Short wavelength has more energy /than long wavelengths of EMR
- Shortest to lonest wavelength of EMR is gamma rays, X-rays, UV radiation,
Visible light, Infrared radiation, microwaves
Interference and Diffraction
- Interference- waves in reacting with each other can cause
- Constructive- waves that align and overlap (in phase)
- Destructive- crest from one source overlaps with the trough (out of phase)
- Diffraction- obstacle/slit, waves behind or diffract around it
- Each slit acts as a new source
Particle Nature of Light
- Photoelectric effect- observation that many metals emit electrons when light shines
upon them
- light energy comes in packets
*, h= plancks constant,   
- packet of lights is called a photon or a quantum of light
*Threshold frequency condition,
- low frequency light does not eject electron because no single photon has minimum
energy to dislodge electron
*, difference between energy of photon and binding
- wave- particle duality of light

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-light appears to behave like a wave and particle
Atomic Spectroscopy and the Bohr Model
- atomic spectroscopy- study of the EMR absorber and emitted by atoms
- when atoms absorbs energy, it often reemits that energy as light
- emission spectrum- single element emits certain colours organized in bright line
Electrons Wave Nature
- De Brogile Wavelength
- wavelength related to KE, faster electron moving= shorter wavelength
*, de Broglie relation
- Uncertainty Principle
- Unable to simultaneously observe both the wave nature and the particle
nature of the electron
- when trying to observe which hole the electron goes through (particle
nature) you lose interference pattern (wave nature)
- electrons particle and wave nature are complementary properties, (exclude
one another)
- Heisenbergs uncertainty principle
- cannot simultaneously measure velocity and position of an electron
- The more accurately you know the position of an electron the less accurately
(smaller x) you know its velocity( v) and vice versa
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