Electrons and energy levels

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  • Created by: Ami_Bull
  • Created on: 22-02-16 16:30
What is a quantum of energy?
A small packet of discrete energy
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What is a photon?
A discrete packet of electromagnetic energy
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How can you calculate the energy carried by each photon? (2 equations)
E=hf E=hc/lamda
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What is the intesity of electromagnetic radiatin?
energy transferred per unit time per unit area
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What does intesity depend on?
energy carried by a photon, the number of photons transferred and the area that they're incident on
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What is the inverse square law?
When intensity is inversley proportional to the square of the distance from the source
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How do you convert joules into eV?
divide J by 1.6x10-19
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How do you convert eV to J?
Multiply eV by 1.6x10-19
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How do we calculate the work done in eV?
W=VQ
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What two types of energy does an electron have?
Kinetic and elastic potential enrgy
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Why do electrons have less energy closer to the nucleus?
Work has to be done to move the electron away from the nucleus (as opposite charges attract)
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When an electron absorbs a photon it can...
Move up an energy level
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When an electron moves down an energy level it...
Emits a photon
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What are quantisised energy levels?
Energy levels with fixed energy values
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What is the ground state?
When electrons in an atom are in their lowest energy state
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What is excitation?
When an electron in an atom moves to a higher energy level after absorbing energy
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Define ionisation
When an atom gains o loses an electron and becomes charged
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What is diffraction grating?
a piece of transparent material ruled with very closely spaced lines used to see the diffraction of light
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What is a continuous spectrum?
When all frequencies of radiation or colours of light are possible
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What is a line spectrum?
A spectrum of discrete coloured lines of light
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What is an emission spectrum?
a bright spectrum seen when photons are emitted by atoms
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When you hold salts over a bunsen burner why do they show a colured flame?
Electrons all from one energy level to another emitting a photon that matches that particular colour of light
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What is an absorbtion spectrum?
A spectrum of dark linesseen on a coloured background produced when a gas absorbs photons
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What is fluorescnece?
when a substance absorbs short wavelength electromagnetic radiation and emits it at a longer wavelength radiation
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What is a fluorescent tube?
A type of light blb that gives out light when its inner coating fluoresces
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What is thermionic emission?
When free electrons are released from a heated filament
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What is plasma?
A mixture of ions and electrons in a gas
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What vapour is inside fluorescent tubes?
mercury
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What coats the inside of a fluorescent tube?
Phosphors
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What is the process of thermonic emission?
Accelration (cathode>anode)_mercury vapour_.collisons_excitation/ionisation_plasma_ground state_photons UV radiation_phosphor coating_absorbed_energy emitted_visible light and heat
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Other cards in this set

Card 2

Front

What is a photon?

Back

A discrete packet of electromagnetic energy

Card 3

Front

How can you calculate the energy carried by each photon? (2 equations)

Back

Preview of the front of card 3

Card 4

Front

What is the intesity of electromagnetic radiatin?

Back

Preview of the front of card 4

Card 5

Front

What does intesity depend on?

Back

Preview of the front of card 5
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