Electromagnetic Radiation & Atomic Spectra Flashcards
electromagnetic radiation can be described…
in terms of waves and characterised in terms of wavelength and frequency.
relationship between wavelength and frequency
c=fλ
what is the electromagnetic spectrum?
the different types of radiation arranged in order of wavelength
wavelengths of visible light are normally expressed in…
nanometres (nm)
What is meant by dual nature?
electromagnetic radiation can be described as a wave and as a particle (photons)
When electromagnetic radiation is absorbed or emitted…
energy is gained or lost by electrons within the substance,
the energy associated with a single photon is given by…
E=hf
or
E=Lhc/λ
units of energy
kJmol-1
when energy is transferred to atoms…
electrons within the atoms may be promoted to higher energy levels.
when does an atom emit a photon of light energy?
when an exited electron moves from a higher energy level to a lower energy level.
the light energy emitted by an atom produces…
a spectrum that is made up of a series of lines at discrete energy levels.
(this provides evidence for the existence of energy levels)
each element in a sample produces…
characteristic absorption and emission spectra
these spectra can be used to identify and quantify the element.
In absorption spectroscopy, electromagnetic radiation is directed at…
an atomised sample. Radiation is absorbed as electrons are promoted to higher energy levels.
An absorption spectrum is produced by…
measuring how the intensity of absorbed light varies with wavelength.
In emission spectroscopy, high temperatures are used to…
excite electrons within atoms.
