chemistry - 1.1 Flashcards
How can electromagnetic radiation be described?
In terms of waves and characterised in terms of wavelength and/or frequency.
What is the relationship between wavelength, frequency and speed of light?
c = f lambda
What is known as the electromagnetic spectrum?
The different types of radiation arranged in order of wavelength.
What are wavelengths of visible light normally expressed in?
Nanometres.
What can electromagnetic radiation be described as?
A wave (has a wavelength and frequency), and as a particle, and is said to have a dual nature.
When electromagnetic radiation is absorbed or emitted by matter, what does it behave like?
A stream of particles - known as photons.
What does a photon carry?
Quantised energy proportional to the frequency of radiation.
What happens when a photon is absorbed or emitted?
Energy is gained or lost by electrons within the substance.
What can photons in high frequency radiation transfer?
Greater amounts of energy than photons in low frequency radiation.
The energy associated with a single photon is given by:
What is the energy associated with a single photon given by?
E=hf or E=hc/lambda
What is the energy associated with one mole of photons given by?
E=Lhf o rE=Lhc / lambda
What units is energy often given in?
kJ mol-1
When energy is transferred to atoms, what may happen to electrons within the atoms?
They may be promoted to higher energy levels.
When does an atom emit 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?
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.
