Exam 2 Lecture 5 Flashcards
Define A “quantum”
the smallest quantity or packet of a given form of electromagnetic radiation
Quantum Effects
1900: Max Planck
Energy is released/absorbed only in discrete “units”, “packets”, or “quanta”
Planck’s Constant
h=6.62607004 × 10-34 m2 kg / s
the photoelectron effect
Einstein
refers to the emission, or ejection, of electrons from the surface of, generally, a metal in response to incident light.
Einstein’s photons
Electromagnetic radiation behaves as if composed of a stream of particles, or “photons”
energy of 1 photon
The energy of one “photon” = the energy of one “quantum”
Light behaving as a wave
LIght behaving as a particle
Light behaving as both a wave and a particle:
Two things are quantized
Explain why
matter and energy
There isn’t such a thing as half an H atom
There isn’t such a thing as half a photon
Formula for energy of a photon
E=nhv
n=number of photons
h=6.62607004 × 10-34 m2 kg / s
v=frequency in hertz (or 1/s)
Energy of a single photon
E=hv
h=6.62607004 × 10-34 m2 kg / s
v=frequency in (1/s)
emission specrtrum
a spectrum of the electromagnetic radiation emitted by a source.
absorbtion spectrum
a spectrum of electromagnetic radiation transmitted through a substance, showing dark lines or bands due to absorption of specific wavelengths.
line spectrum
an emission spectrum consisting of separate isolated lines.
Who is this?
Niels Bohr
What did Bohr do?
He made a model for the hydrogen atom
Monochromatic light:
light (radiation) of a single wavelength (ex.: laser light)
Visible light:
composed of light (radiation) of many different wavelengths
What gives rise to all of the color that we observe?
Electron excitation and relaxation
The heat of the flame ___________. When the electron ______back to the _______, energy is released as visible light.
excites an electron to a higher energy state
relaxes
“ground state”
Calculate energy with wavelength
What happens to a line spectra when you shine visible light through a prism?
It reveals the colors involved
Name Bohr’s postulates
Bohr’s postulates
- Only electron “orbits” of certain energies are allowed (the energy of an e - are allowed (the energy of an e is quantized)
- An electron in a An electron in a “permitted orbit permitted orbit ” has a specific energy (an allowed energy “state”)
- _______
An electron in an allowed state is stable An electron in an allowed state is stable and will not radiate energy
Bohr’s postulates
- Only electron “orbits” of certain energies are allowed (the energy of an e - are allowed (the energy of an e is quantized)
- ________
- An electron in an allowed state is stable An electron in an allowed state is stable and will not radiate energy
2 An electron in a An electron in a “permitted orbit permitted orbit ” has a specific energy (an allowed energy “state”)
Bohr’s postulates
- ____________
- An electron in a An electron in a “permitted orbit permitted orbit ” has a specific energy (an allowed energy “state”)
- An electron in an allowed state is stable An electron in an allowed state is stable and will not radiate energy
Only electron “orbits” of certain energies are allowed (the energy of an e - are allowed (the energy of an e is quantized)
n=1 is what state
n>1 is what state?
n=1 is what state
