Download atomic emission spectrum

Modern Atomic Theory
Quantum Theory and the
Electronic Structure of Atoms
Chapter 11
Properties of Waves
Properties of Waves
The speed (u) of the wave = l x n
electromagnetic waves
Electromagnetic
radiation is the emission
and transmission of energy
in the form of
electromagnetic waves.
All electromagnetic radiation
lxn=c
A photon has a frequency of 6.0 x 104 Hz. Convert
this frequency into wavelength (nm). Does this frequency
fall in the visible region?
Why all this info about light???
• atomic emission spectrum of an element.
• The emission spectrum of white light is continuous.
• Atomic emission spectra consist of relatively few lines and
are discontinuous.
• Each line corresponds to a specific amount (quantum) of
energy being emitted.
• The emission spectra for each element is
unique.
Classical physics does not explain the
emission spectra of atoms.
Energy (light) is emitted
or absorbed in discrete
units (quantum).
E=hxn
Planck’s constant (h)
h = 6.63 x 10-34 J•s
When copper is bombarded with high-energy electrons,
X rays are emitted. Calculate the energy (in joules)
associated with the photons if the wavelength of the X
rays is 0.154 nm.
http://www.youtube.com/watch?v=oUolVZIuv18
Photoelectric Effect
• Light quanta are called photons.
• Light has a “dual nature” as it exhibits wave-particle
behavior.
• In the photoelectric effect metals eject electrons
when light shines on them.
• Einstein used his particle theory of light to explain the
photoelectric effect.
• He recognized there is a threshold value of energy below
which this effect does not occur.
• Since E = h x v, if the frequency and therefore the energy of
photons is too low, the photoelectric effect does not occur.
http://player.discoveryeducation.com/index.cfm?guidAssetId=B2E7CD0F-A754-4BA4-8D00-B0DE326F1038&blnFromSearch=1&productcode=US