U1: Topic 1 Electromagnetic Radiation & Atomic Spectra Flashcards
What is electromagnetic radiation?
Form of energy
Described as waves
Different types of electromagnetic radiation will have …
Different wavelengths and frequencies
what is the wavelength?
Distance between two adjacent crests of a wave.
What is the frequency?
Number of waves to pass a fixed point per second. (sometimes measured in Hertz)
If wavelength increases then the frequency must …… as the speed is ……
Decrease
Constant
Radiation with a high frequency has?
A small wavelength
Radiation with a low frequency has?
A large wavelength
What is a photon?
when electromagnetic radiation interacts with matter there is a transfer of energy to the matter. Energy is transferred in small bundles called “quanta”.
What does a photon carry?
quantised energy that is proportional to the frequency of radiation.
What is planck’s constant?
Constant linking photon energy to frequency
Photons in high frequency radiation can transfer greater amount of energy than what?
Photons in low frequency radiation
What happens when a photon is absorbed?
Energy is gained by the electrons in a substance
What happens when a photon is emitted?
Energy is lost by electrons in the substance
What is avagrados constant?
Number of formula units present in one mole of a substance
What happenes when energy is transferred to atoms?
Electrons within the atoms may be promoted to higher levels
What happens to the promoted electron?
Becomes unstable and falls back down to the lower level. As this happens it emits a photon of light energy.
If emitted energy falls within the visible spectrum what happens?
A colour will be observed
What do some gaseous elements do when subjected to high voltages?
Emit light
Light energy emitted by an atom can produce a spectrum which is made up of a series of lines at discrete energy levels. What does this prove?
The existence of energy levels
The electrons that fall from different energy levels emit different energy why?
Because the energy levels are of a fixed energy
Why can electrons which have fallen from high level to lower levels only have certain fixed frequencies (specific colours) ?
Because the energy levels are fixed.
The frequency and wavelengths of any radiation is determined by it’s energy
Each element has characteristic what?
Absorption and emission spectrum which can be used to identify and quantify the elements
The concentration of an element within a sample is related to?
the intensity of light emitted or absorbed.
In emission spectroscopy what are high temperatures used for?
To excite the electrons within the atoms
