Chapter 7 Flashcards
how has much of our understanding of the electronic structure of atoms came to be
as a result of the analysis of light emitted or absorbed by substances
what did Sir Isaac Newton discover about white light
that it can be broken down into components with different colors from red to violet by the action of a prism
properties of waves (maxwell)
suggested that light consists of “waves” and that the energy is spread over space like an oscillating liquid
amplitude
the max displacement (height of wave above the centerline)
wavelength
represented by lamda, is the peak-to-peak distance
frequency
represented by nu, the number of wavelengths that pass a given point in 1 second
units of frequency
are cycles per second (s-1) or hertz (Hz)
c
the speed of light (product of wavelength + frequency)
- speed of a light wave in a vacuum is constant
- c=3x10^8 ms-1
how are wavelength and frequency related
wavelength and frequency are inversly related
electromagnetic waves
all visible light consists of electromagnetic waves
- there are oscillating electric and magnetic fields
- these fields are perpendicular to the direction of the light
equation for electromagnetic radiation
c=(lamda)(nu)
electromagnetic spectrum
electromagnetic radiation has a large range of wavelengths and frequencies with no known limit
blue light
has a smaller wavelength but a smaller frequency
black body radiation
as a body is heated, it glows more brightly and the color of light it gives off changes from red through orange and yellow to white
incandescence
rhe emission of light (visible electromagnetic radiation) from a hot body due to its temperature
how did planck describe black body radiation
- it is not possible to put any arbitrary amount of energy into an oscillator, the energy must be quantized
- oscillator must gain and lose energy in “packets” or “quanta” of magnitude (hv) where h is plancks constant (6.63x10^-34
plancks constant
6.63x10^-34
oscillator
a machine that generated oscillating electric currents and voltages by nonchemical means
classical oscillator
has continuous valves of energy and can gain or lose energy in arbitrary amounts
formula for an oscillating atom releasing energy
E=hv
quantum oscillator
has discrete energy levels and can only gain or lose energy in discrete energy levels and can only gain or lose energy in discrete amounts
Heinrich Hertz
showed that electrons are ejected from a metal when it is exposed to ultraviolet radiation
photoelectric effect
- if radiation frequency is less than the threshold value (Vo) of the metal, than no electrons are emitted no matter how intense
- if radiation frequency is greater than or equal to the threshold value (Vo) than electrons are emitted
- if increase intensity of light (more pockets of light) more electrons are emitted but there is no change to the max kinetic energy of the electron
Albert Einstein’s statements on light ect
- light is quantizes as photons
- light has properties of both waves and matter
- neither the wave nor the particle view alone is a complete description of light (particle-wave duality of light)
particle-wave duality of light
neither the wave nor the particle view alone is a complete description of light
threshold value
a point in which a change is executed
can white light be seperated
yes, by a prism. and this produces a continuous range of colors which merge together