Electromagnetic Radiation And Atomic Spectra Flashcards
Electromagnetic radiation
Can be described in terms of waves and characteristics in terms of wavelength and/or frequency
Electromagnetic spectrum
The different types of radiation arranged in order of wavelength
Why is electromagnetic radiation described as having a dual nature?
Can be described as a wave and as a particle
What happens when electromagnetic radiation is absorbed or emitted by matter?
It behaves as a stream of particles known as photons
How much energy is in a photon?
It has proportional energy to the frequency of radiation
What effect does a photon being absorbed or emitted have on an electron?
Energy is gained or lost by electrons within the substance.
What happens when energy is transferred to atoms?
Electrons within the atoms may be promoted to higher energy levels.
How does an atom emit a photon of light?
An excited electron moves from a higher energy level to a lower energy level a photon of light is emitted.
What provides direct evidence of the existence of energy levels?
The light energy emitted by an atom produces a spectrum that is made up of a series of lines at discrete (quantised) energy levels.
How can we identify and quantify an element?
Each element in a sample produces a characteristic adsorption an emission spectra.
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.
Emission spectroscopy
High temperatures are used to excite the electrons within the atoms. As the electrons drop to lower energy levels, photons are emitted. An emission spectrum of a sample is produced by measuring the intensity of light emitted at different wavelengths.
Atomic spectroscopy
The concentration of an element within a sample is related to the intensity of light emitted or absorbed.
