Properties of Waves:
- Wave : a vibrating disturbance by which enerlgy is transmitted.
- Wavelength: distance between identical points on a wave ( crest to crest ).
- Frequency : (v) number of waves that pass through a point in 1 second.
- Amplitude: height of wave from midline of wave to crest.
- Node: Poing of zero amplitude
Speed of Waves
- Electro magnetic radiation travels at the speed of light ( c ).
- the speed is relatied to the wave lenght and frequency.
- wavelength is measured in meters.
- speed of light ( 3.0 x 10^8).
- frequency ( s^-1 or Hz ).
- H= Herts ( type of measurement ).
- In this formula wave length and frequency are INDIRECTLY related.
Light as a particle
Max Planck (1900) discovered that stoms and molecules release energy in quantities called quant ( small bursts of energy we see in the form of light ) .
- He used the formula [ E=hv ].
- In this formula energy and frequency are DIRECTLY RELATED.
- E = energy of vibrating system measured in J.
- h= planck's constant ( 6.626 x 10^-34 ).
- v= frequency.
Albert einstein ( 1905 )
Albert Einstein improved Plancks theory by studying the photoelectric effect. He shined a UV light on a metal, the electrons were ejected from the surface of the metal. The light contains tiny lumps of light particles called PHOTONS.
So what is light?
Presently we accept the dual nature of light. " Light is a collection of photons ( particles ) moving through space as electromagnetic waves!
What does it do to the atom?
After his discover of the nucleus Rutherford argued that accelerating charged electrons release EMR ( electromagnetic radiation ) and would collapse on the nucleus completely destroying the atom itself!
So what is light?
Presently we accept the dual nature of light. " Light is a collection of photons ( particles ) moving through space as electromagnetic waves!
What does it do to the atom?
After his discover of the nucleus Rutherford argued that accelerating charged electrons release EMR ( electromagnetic radiation ) and would collapse on the nucleus completely destroying the atom itself!
Neils bohr (1913)
Mr.Bohr used Rutherford's AND Planck's work to design a model for the lovely hydrogen atom.
His model mimicked the the planets moving around the sun with the planets being electrons and the sun is the nucleus. To solve the problem he ran into with physics Bohr suggested that an electron could only occupy CERTIAN orbits/ energy. Borh stated that energy was quantisized, which meant that the electrons can occupy only certian orbits. His model also explaind how the hydogen atoms release color while absorbing energy at the same time.
Borh used the formula-----------------------> E = -Rhc / n^2
His model mimicked the the planets moving around the sun with the planets being electrons and the sun is the nucleus. To solve the problem he ran into with physics Bohr suggested that an electron could only occupy CERTIAN orbits/ energy. Borh stated that energy was quantisized, which meant that the electrons can occupy only certian orbits. His model also explaind how the hydogen atoms release color while absorbing energy at the same time.
Borh used the formula-----------------------> E = -Rhc / n^2
- E= energy ( J per atom )
- R = ryderberg's constant ( 1.097 x 10^7 )
- h= Planck's constant ( 6.626 x 10^-34)
- c= speed of light ( 3.0 x 10^8 )
- n= principle quantum #
Elements when in gas phast release light when linked with a voltage source.
Only CERTIAN wavelengths of light are released.
The wavelength must then be passed through a prism to separate a line.
The 'finger print' of an element is a specific line of the spectrum, they use the spectrum to identify unknown elements.
Only CERTIAN wavelengths of light are released.
The wavelength must then be passed through a prism to separate a line.
The 'finger print' of an element is a specific line of the spectrum, they use the spectrum to identify unknown elements.
Information was presented in class.