• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Spectroscopy

Extracts from this document...

Introduction

Chemistry Unit 2 Spectrometry Katie Bennett Spectrum Definition: The several coloured and other rays of which light is composed, separated by the refraction of a prism or other means, and observed or studied either as spread out on a screen, by direct vision, by photography, or otherwise. Introduction to Spectroscopy Spectroscopy is a complex art - but it can be very useful in helping scientists understand how an object like a black hole, neutron star, or active galaxy is producing light, how fast it is moving, and even what elements it is made of. A spectrum is simply a chart or a graph that shows the intensity of light being emitted over a range of energies. Spectra can be produced for any energy of light - from low-energy radio waves to very high-energy gamma-rays. Spectra are complex because each spectrum holds a wide variety of information. For instance, there are many different mechanisms by which an object, like a star, can produce light - or using the technical term for light, electromagnetic radiation. Each of these mechanisms has a characteristic spectrum. ...read more.

Middle

Below we see the spectrum, the unique fingerprint of hydrogen. These bright lines are called emission lines. Remember how we heated the hydrogen to give the atoms energy? By doing that, we excited the electrons in the atom - when the electrons fell back to their ground state, they gave of photons of light at hydrogen's characteristic energies. If we altered the amount or abundance of hydrogen gas we have, we could change the intensity of the lines, that is, their brightness, because more photons would be produced. But we couldn't change their colour - no matter how much or how little hydrogen gas was present, the pattern of lines would be the same. Hydrogen's pattern of emission lines is unique to it. The brightness of the emission lines can give us a great deal of information about the abundance of hydrogen present. This is particularly useful in a star, where there are many elements mixed together. Each element in the periodic table can appear in gaseous form and will each produce a series of bright emission lines unique to that element. ...read more.

Conclusion

From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star. Emission lines can also tell us about the magnetic field of the star. The width of the line can tell us how fast the material is moving, giving us information about stellar wind. If the lines shift back and forth, it means that the star may be orbiting another star - the spectrum will give the information necessary to estimating the mass and size of the star system and the companion star. If the lines grow and fade in strength we can learn about the physical changes in the star. Spectral information, particularly from energies of light other than optical, can tell us about material around stars. This material may have been pulled from a companion star by a black hole or a neutron star, where it will form an orbiting disk. Around a compact object (black hole, neutron star), the material in this accretion disk is heated to the point that it gives off X-rays, and the material eventually falls onto the black hole or neutron star. It is by looking at the spectrum of X-rays being emitted by that object and its surrounding disk, which we can learn about the nature of these objects. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physical Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a star student thought of this essay

3 star(s)

Response to the question

The candidate has attempted to give a fairly detailed response and it is evident that they have taken the time to undergo independent research. This is shown by the inclusion of a bibliography at the end of the essay. By ...

Read full review

Response to the question

The candidate has attempted to give a fairly detailed response and it is evident that they have taken the time to undergo independent research. This is shown by the inclusion of a bibliography at the end of the essay. By taking the time to throughly research your topic, you demonstrate dedication and an interest in your subject.

Level of analysis

The candidate starts this piece for work by stating a definition, this can be useful when writing about a scientific topic, however the definition given is unclear, which makes me question the candidate’s understanding. In addition to this the candidate does not give a clear introduction. You should always introduce the topic you are discussing, a good introduction should introduce your essay title, state the topics you plan to discuss and engage the reader, which you can do by stating interesting facts or even a quote that is related to your set topic. By catching the readers attention, you ensure that they will invest time in reading all of your essay instead of skimming through it. In addition to this the candidate also fails to write any kind of conclusion, which is a mistake. You should always try to conclude your work. A good conclusion should summarise key points from within your essay and should include a personal response. This allows you to bring the essay to a close.

Quality of writing

The language used by the candidate is a little too simplistic for this level of qualification and very few technical terms are used. For example there is a point in the essay in which the candidate states that the electromagnetic spectrum covers all energies of light, they should have used the term electromagnetic radiation instead of word light which is misleading. This shows that the candidate’s level of understanding of these topics is only average. Furthermore there are some errors which punctuation and grammar.


Did you find this review helpful? Join our team of reviewers and help other students learn

Reviewed by pictureperfect 13/07/2012

Read less
Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Physical Chemistry essays

  1. Marked by a teacher

    Heat of Neutralization. Objective: To investigate the ...

    5 star(s)

    temperature 24.0 26.2 28.2 26.9 25.0 Change in temperature 1.4 3.6 5.6 4.5 1.5 (A large scale graph would be attached at page 11) The maximum change in temperature was 5.8 degree Celsius. The volume of alkali added at the time while maximum change in temp.

  2. Marked by a teacher

    Experiment investigating hydrogen bonding in different chemicals.

    5 star(s)

    10cm3 of trichloromethane was added to the ethanol in the beaker and mixed well. 4. The highest temperature of the mixture was measured using a thermometer. D. To measure the strength of hydrogen bonds formed between molecules of ethyl ethanoate and trichloromethane 1.

  1. Determination of isoelectric point of protein (casein).

    However, an excessive reduction in the concentration of hydrogen ions causes the amino group, to lose hydrogen ions. In either direction, the 3-D tertiary structure of the protein which is held together by electrostatic hydrogen bond and ionic bonds are hence broken and consequently, the function of the casein is altered.

  2. Investigation to analyse some fruit and vegetable juices for the contents present in them.

    Xanthoproteic test To the protein sample, add few drops of conc. HNO3. A yellow precipitate confirms the presence of proteins. This test is based upon the formation of yellow coloured aromatic nitro compounds which are produced by the action of nitric acid on the benzene rings present in some of the - amino acids (tyrosine, phenylamine, etc.)

  1. Determination of the content of Mg (OH)2 in an indigestion remedy by back titration ...

    (1.5 cm3 /1000) x 0.5 mol dm-3 = 7.5 x 10-4 mol (NaOH used) Moles of HCl - Moles of NaOH = Moles of HCl remaining (N.B mol of NaOH = mol of HCl as ratio 1:1) 5. 0.025 mol - 1.875 x 10-3 mol = 0.023125 mol 6.

  2. Drug: Antacid Effectiveness Analysis To determine the neutralizing ability of antacids in different ...

    ACTAL Composition Na polyhydroxyaluminium monocarbonate hexitol complex (equiv to Al(OH)3 216 mg) Dosage Allow two tablets to dissolve on the tongue as required, up to 8 times daily. Do not exceed 16 tablets in 24 hours. Administration Should be taken on an empty stomach (Take 1/2-1 hr after meals.).

  1. Identification of amino acids by using paper chromatography

    sprays was use in a fume cupboards but I need to have a box in the fume cupboard in the box I will place the chromatography paper inside the box then I will used the ninhydrin sprays in the box inside the fume cupboard this is due to health and

  2. Outline and examine some uses of different metals through history, including contemporary uses, as ...

    The most active metals (and Na) are located in group one on the left side of the table. In general their reactivity increases down the group. 3. The next most active metals belong to group two. Once again reactivity increases down the group.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work