Elements Of Life: Spectroscopy Flashcards
What is the order of the EM spectrum with increasing frequency?
Radio, Micro, IR, Light, UV, X, Gamma
What is the order of the EM spectrum with increasing wavelength?
Gamma, X, UV, Light, IR, Micro, Radio
What is the order of the EM spectrum with increasing energy?
Radio, Micro, IR, Light, UV, X, Gamma
Which EM wave has the longest wavelength
Radio
Which EM wave has the shortest wavelength
Gamma
Which EM wave has the highest frequency
Gamma
Which EM wave has the lowest frequency
Radio
Which EM wave has the highest energy
Gamma
Which EM wave has the lowest energy
Radio
Definition of quantisation
Specific energy value
Name 2 types of spectra
Absorption
Emission
What does energy absorbed by an electron do
Causes electrons to be excited = promote ( jump ) to higher energy levels
When electrons are excited state what does this result in
(Atom) = unstable
When electrons are in excited states ( unstable ) what do they do
Electrons drop back down = emitting photo ( light )
What does energy levels being quantised ( having a specific energy value ) result in
Lines of specific frequencies / wavelengths
E = hv
List similarities between the 2 types of spectra (2)
- Lines in both = closer together at high frequencies
- Both are LINE spectra
- E=hv
- lines of specific frequencies
List differences between the 2 spectra
- Absorption = coloured back ground - Emission = black background
What do energy absorbed and energy emitted always have to be
The exact same
Energy absorbed = energy emitted
What is the 6 marker answer need to learn for line spectra questions
- Energy absorbed causes electrons to be excited
- = promotion ( jump ) to higher energy levels
- Excited states = unstable = electrons drop back down emoting photon ( light )
- Energy levels = quantised ( specific energy value )
- = lines of specific frequencies / wavelengths
- E = hv
- Draw diagrams
Equation for c, speed of light
c=v lamda
Speed of light = frequency x wavelength ( m )
1st equation for E, energy ( J )
E=hv
Energy = planks constant x frequency
2nd equation for E, energy ( J ) when only given the wavelength
E= hc/ lamda
Energy (J) = ( planks constant x speed of light ) / wavelength
How to go from J -> KJmol^-1
Divide by 1000
Then…
Multiply by Avogadros constant
How to go from KJmol^-1 -> J
Divide by Avogadros constant
Then….
Multiply by 1000
What does ‘c’ stand for
Speed of light
What does ‘h’ stand for
Planks constant
Describe emission spectra
- Coloured lines on black background
- Lines = specific to an element
- Because energy gaps = unique
- Compare with known data
How lines used to identify elements
- Each element = own specific energy level
- = Different energy gaps
- = Different frequency lines
- Compare frequencies of lines with known data
How lines formed + why they have specific frequencies
- Atoms absorb energy
- Electrons promote to higher energy level
- Atom = unstable = electrons drop back down emitting light
- E=hv ( energy dropped = proportional to frequency )
