Ionisation - Spectroscopy Flashcards
What does a complete spectrum consist of and what is it called?
It is composed of all visible wavelengths of light and is called a continuous spectrum.
How is a complete light spectrum formed?
When light is shone through a slit and the resulting beam is shone through a prism onto a screen a rainbow of separated colours is seen.
Name the types of E.M radiation from highest energy to lowest
Gamma rays
X rays
ultraviolet
Visible (blue)
Visible (yellow)
Visible (red)
Infrared
Microwaves
Radio waves
What is monochromatic light?
Light consisting of only one wavelength.
How is frequency related to the velocity and wavelength of light.
F=V/wavelength
How is frequency related to the energy of the radiation?
As the frequency increases so does the energy of the E.M radiation and is expressed as E=hF where “h” is Planck’s constant
How is an emission spectrum created?
A gas source is excited (by subjecting it to an electric current at a low pressure) until it begins to emit light which then passes through a prism and onto a screen.
Give an example where subjecting a gas to a potential difference to emit light is used?
Advertising signs and sodium vapour street lamps.
How is an absorption spectrum formed.
By shining white light through a gas and projecting it through a prism onto a screen.
What is the appearance of an emission spectrum?
This consists of a series of bright, coloured, discrete lines on a black background.
What is the appearance of an absorption spectrum?
A series of discrete black lines upon a bright, coloured background.
How are absorption and emission spectra related?
The bright lines on the emission spectrum correspond exactly to the position of the dark lines on an absorption spectrum for the same light source.
What type of spectra are emission and absorption spectra?
Line spectra.
What does the hydrogen emission spectrum consist of?
A number of separate sets of lines.
Describe the trend seen in each set of lines in the hydrogen spectrum.
The intervals between the between the lines gets smaller as the frequency increases until they coalesce.
What are the three series’s in the hydrogen spectrum and in what regions of the spectrum do they reside?
Paschen & Brackett - infrared.
Balmier - visible.
Lyman - ultraviolet.
What did max Planck state His quantum theory and what is the implication of this theory?
That energy couldn’t be held by particles or atoms in any arbitrary amount but only in specified amounts called quanta.
A particle cannot change its energy continuously but only by a series of steps.
How did Niels Bhor apply max plank’s quantum theory to the hydrogen spectrum?
By suggesting that electrons can only exist in certain defined energy states and that they can only move between these states by absorbing or emitting quanta of energy in the form of radiation. The lower energy states correspond to inner orbits and the higher energy states the outer.
How are lines in the emission and absorption spectrum caused?
Absorption - an electron is excited by absorbing a quantum of energy and goes from a lower energy level to a higher one.
Emission - a line in the emission spectrum results from an excited electron in a higher energy level falling to a lower one, releasing a quantum of energy which takes the form of light of a certain frequency.
How are energy levels labelled?
The energy level closest to the nucleus is called the n=1 energy level and an electron in this level is in its ground state. The next orbit has the quantum number 2 (n=2) etc.
When is an atom ionised?
When an electron moves in the layman series from the n=1 energy level to the point where they coalesce n=infinity (the convergence limit) it has escaped the pull of the nucleus and has become an ion.
How can the ionisation energy be calculated from an emission spectrum?
The frequency of the convergence limit in the in the lyman series can be used to calculate the ionisation energy using E=hF where “h” is Planck’s constant and “f” is the frequency of convergence.
Explain the origins of the first four lines in the balmier series.
1st: N=3 falls to n=2
2nd: N=4 falls to n=2
3rd: N=5 falls to n=2
4th: N=6 falls to n=2
What does the hydrogen emission spectrum consist of?
A number of separate sets of lines.
Describe the trend seen in each set of lines in the hydrogen spectrum.
The intervals between the between the lines gets smaller as the frequency increases until they coalesce.
What are the three series’s in the hydrogen spectrum and in what regions of the spectrum do they reside?
Paschen & Brackett - infrared.
Balmier - visible.
Lyman - ultraviolet.
What did max Planck state His quantum theory and what is the implication of this theory?
That energy couldn’t be held by particles or atoms in any arbitrary amount but only in specified amounts called quanta.
A particle cannot change its energy continuously but only by a series of steps.
How did Niels Bhor apply max plank’s quantum theory to the hydrogen spectrum?
By suggesting that electrons can only exist in certain defined energy states and that they can only move between these states by absorbing or emitting quanta of energy in the form of radiation. The lower energy states correspond to inner orbits and the higher energy states the outer.
How are lines in the emission and absorption spectrum caused?
Absorption - an electron is excited by absorbing a quantum of energy and goes from a lower energy level to a higher one.
Emission - a line in the emission spectrum results from an excited electron in a higher energy level falling to a lower one, releasing a quantum of energy which takes the form of light of a certain frequency.
How are energy levels labelled?
The energy level closest to the nucleus is called the n=1 energy level and an electron in this level is in its ground state. The next orbit has the quantum number 2 (n=2) etc.
When is an atom ionised?
When an electron moves in the layman series from the n=1 energy level to the point where they coalesce n=infinity (the convergence limit) it has escaped the pull of the nucleus and has become an ion.
How can the ionisation energy be calculated from an emission spectrum?
The frequency of the convergence limit in the in the lyman series can be used to calculate the ionisation energy using E=hF where “h” is Planck’s constant and “f” is the frequency of convergence.
Explain the origins of the first four lines in the balmier series.
1st: N=3 falls to n=2
2nd: N=4 falls to n=2
3rd: N=5 falls to n=2
4th: N=6 falls to n=2
