Electromagnetic Radiation and Atomic Spectra Flashcards
How can electromagnetic radiation be described
Electromagnetic radiation can be described in terms of waves and characterised in terms of wavelength and / or frequency
Which equation connects velocity of light, wavelength and frequency
The relationship between these quantities is given by c = f λ .
What is the electromagnetic spectrum
The different types of radiation arranged in order of wavelength is known as the
electromagnetic spectrum.
What are wavelengths of visible light expressed in
Wavelengths of visible light are normally expressed in nanometres (nm).
What type of nature does electromagnetic radiation have
Electromagnetic radiation can be described as a wave (has a wavelength and frequency), and as a particle, and is said to have a dual nature.
What are photons
When electromagnetic radiation is absorbed or emitted by matter it behaves like a stream of particles. These particles are known as photons.
What type of energy does a photon carry
A photon carries quantised energy proportional to the frequency of radiation.
What happens to electrons when a photon is absorbed or emitted
When a photon is absorbed or emitted, energy is gained or lost by electrons within the substance
What is the difference between photons in high frequency radiation than photons in low frequency radiation
The photons in high frequency radiation can transfer greater amounts of energy than photons in low frequency radiation.
The energy associated with a single photon is given by:
E=hf or E=hc/λ
The energy associated with one mole of photons is given by:
E = Lhf or E = Lhc/λ
What are often the units of energy
kJ mol-1.
What happens when energy is transferred to atoms
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
An atom emits a photon of light energy when an excited electron moves from a higher energy level to a lower energy level.
What does the light energy emitted by an atom produce
The light energy emitted by an atom produces a spectrum that is made up of a series of lines at discrete (quantised) energy levels. This provides direct evidence for the existence of these energy levels.
What does each element in a sample produce
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 what is em radiation directed at
In absorption spectroscopy, electromagnetic radiation is directed at an atomised sample. Radiation is absorbed as electrons are promoted to higher energy levels.
How is an absorption spectrum produced
An absorption spectrum is produced by measuring how the intensity of absorbed light varies with wavelength.
In emission spectroscopy what are high temps used for
In emission spectroscopy, high temperatures are used to excite the electrons within atoms. As the electrons drop to lower energy levels, photons are emitted.
How is an emission spectrum of a sample produced
An emission spectrum of a sample is produced by measuring the intensity of light emitted at different wavelengths.
What is the concentration of an element in atomic spectroscopy related to
In atomic spectroscopy, the concentration of an element within a sample is related to the intensity of light emitted or absorbed.
The radiation types pf electromagnetic spectrum can be put in order of wavelength
EM Radiation. Gamma rays. X rays. UV visible. Infrared red. Microwaves. Radiotv
Wavelength Low < ———————————————— high
Frequency High ————————————————-> low
Energy. High ————————————————-> low
