KA 1: electromagnetic radiation and atomic spectra Flashcards
(15 cards)
What can light be represented as?
-continuous wave
-stream of photons
What does a photon carry?
quantised energy proportional to the frequency of radiation
What happens when energy is transferred to atoms?
electrons within the atoms may be promoted to higher energy levels
what does the light energy emitted by an atom produce?
a spectrum that is made up of a series of lines in discrete energy levels
What does each element in the sample produce?
And what can they be used for?
characteristic absorption and emission spectra
to identify and quantify the element
Describe absorption spectroscopy
e.m. radiation is directed at am atomised sample
radiation is absorbed as electrons are promoted to higher energy levels
Describe emission spectroscopy
high temps are sued to excite the electrons
as the electrons drop to lower energy levels, photons are emitted
Describe atomic spectroscopy
the concentration of an element within a sample is related to the intensity of light emitted or absorbed
What is an absorption spectrum?
produced by measuring…
produced by measuring how the intensity of absorbed light varies with wavelength
What is an emission spectrum?
produced by measuring the intensity of light emitted at different wavelengths
explain how a line is produced in an emission spectra
-electrons excited
-energy emitted
explain why there is a series of lines of discrete wavelengths in the emission spectrum of cadium
different transitions occur
what causes electrons to become excited?
high temps
explain, in terms of electrons, how coloured light is produced when fireworks are ignited (1)
electrons drop to lower energy levels
explain, in terms of energy levels, why red light is emitted by lithium ions when distress flares are burned
-excited electrons drop to lower energy levels
-the difference in energy levels corresponds to the energy emitted
