The Electromagnetic Spectrum And Atomic Spectroscopy Flashcards
What is the electromagnetic spectrum?
The range of frequencies/ wavelengths of electromagnetic radiation
What is electromagnetic radiation? Give e.g’s
A form of energy such as light, X-rays, microwaves.
What is wavelength?
The distance between adjacent crests of a wave.
Lambda
Measured in m, (nm= X10-9m)
What is frequency?
The no. of wavelengths that pass a fixed point in one unit of time.
Nu.
Measured in Hz/ seconds to the negative one.
What is the velocity which all electromagnetic radiation travels at? And what does it equal?
The speed of light (C) .
3X10^8
Measured in metres per second (ms^-1).
C= wavelength X frequency
What is the wavenumber?
Nu bar / one over lambda .
Waves per cm,
Units = cm^-1
What happens when electromagnetic radiation interacts with matter ?
There is a transfer of energy from the radiation to the receiving body (e.g. Sun bathing)
In what way can energy be transferred?
In small bundles only (quanta)
What theory did Max Planck develop? What eqn comes from this?
Under certain circumstances electromagnetic radiation may be regarded as a stream of particles. These particles are called photons.
E=h X nu OR E=Lh(nu) OR E= LhC/lambda where h= planks constant (6.63X10^-34)
What happens if a white beam of light is passed through a prism? And what if the light source is supplied by sodium chloride?
1) a continuous spectrum is seen
2) the spectrum turns out not to be a continuous spectrum but a series of lines of diff wavelengths and thus of diff colours
What is atomic emission spectra?
Spectra that show energy being given out by an atom/ion. The pattern of lines in a spectrum is characteristic of each element and can be used to identify it.
What happens if a beam of continuous radiation (I.e. White light) is directed through a gaseous sample of an element , and on a spectrum?
The radiation that emerges has a certain wavelength missing.
This shows up as dark lines on a continuous spectrum + is called an atomic absorption spectrum.
This also provides a pattern that can often be used in identification
