ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: luken93 on April 30, 2010, 08:16:10 pm
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Firstly, do all metal cations produce a characteristic flame colour?
If so, why/why not.
Also, are you able to predict the colour that an element will produce?
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Every different metal produces a different flame colour as every different metal absorbs a specific wavelength of light- let me try and explain (I'm horrible at explaining :P). A specific wavelength of light produces energy that "excites" the valence electrons of a particular metal, and they jump up to a higher energy level. As this level is unstable, it drops back down and releases energy, which is this flame colour you see :P So in a nutshell, every metal has a different wavelength of light that it can absorb.
And yes you can predict the colour a metal will produce- but some release light that isn't in the visible spectrum (eg. UV light), so we cannot see them.
Sorry if this isn't the answer you were looking for, but I gave it a shot :)
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I think only around 22 metals emit visible light from a flame test.
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Every different metal produces a different flame colour as every different metal absorbs a specific wavelength of light- let me try and explain (I'm horrible at explaining :P). A specific wavelength of light produces energy that "excites" the valence electrons of a particular metal, and they jump up to a higher energy level. As this level is unstable, it drops back down and releases energy, which is this flame colour you see :P So in a nutshell, every metal has a different wavelength of light that it can absorb.
And yes you can predict the colour a metal will produce- but some release light that isn't in the visible spectrum (eg. UV light), so we cannot see them.
Sorry if this isn't the answer you were looking for, but I gave it a shot :)
yeh thats fine, I understand how flame colours work, but I just presumed that every single one would because certain metals that we have tested have no specific characteristics about them that other metals dont.
I think only around 22 metals emit visible light from a flame test.
is that the number we can see with our own eyes, yet every metal produces a light, just most of them we can't see?
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well..all i know is
potassium - lilac
sodium - yellow
barium - apple green
copper - green
strontium - crimson
calcium - brick red
i think you can find them on wikipedia as well
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
i havent come across a question in the exam that talks about this :P hopefully not XD
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
i havent come across a question in the exam that talks about this :P hopefully not XD
Haha he's doing chem 1&2 I believe :P
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
i havent come across a question in the exam that talks about this :P hopefully not XD
Haha he's doing chem 1&2 I believe :P
correct, one of the questions in our summary report
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Certain temperatures will cause certain metals electrons to jump, then emit a photon. In the flame test for example, some metals wont even give off light, because the energy required for the electron to jump isnt high eneough
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
IMO using the word "restrictions" is too vague.
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I know that some emit light in higher frequencies than are visible during a flame test, and I'm not 100% sure, but I think that some metal cations require a higher level of energy than what is provided by a flame to excite their electrons.
Ok, so to answer the question as to whether all metal cations produce a flame colour, my answer will be:
All metal cations will emit a photon of light, however due to the restrictions of our eyesight we are unable to see most. Also, due to the restrictions of using a bunsen burner, we are unable to generate enough energy to excite the electrons in some elements.
IMO using the word "restrictions" is too vague.
umm okay,
All metal cations will emit a photon of light, however due to the limits of the visible spectrum we are unable to see some of these wavelengths. Also, some cations need more energy than others for the valence electrons to be able to jump to a higher energy level.
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Mmm
"When metal cations release a photon of light following being heated in a Bunsen flame, the photon of light released is at times not within the visible spectrum of light; In this case no visible light is produced. Furthermore Bunsen burners do not provide sufficient energy to excite the electrons of many metal cations. Hence not all metal cations will produce a flame colour in a Bunsen flame test."
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A few problems with the past statements:
The visible spectrum is what we can see with our eyes, therefore the limitation of the measurement in this case is our eyes. You are correct in saying that our eyes are 'restricted' to a certain part of the spectrum, but just word it in a different way, such as 'since our eyes can only detect a certain range of wavelengths..."
Secondly, I am fairly certain vapourised metal atoms will emit light, since the electronic transition at that point is quite low (don't quote me on it, but I am pretty sure that's the case). So I wouldn't say a flame is insufficient energy-wise. You would be more worried about light being emitted in the infrared and UV region that can't be seen by the human eye.
Also, another main problem with the 'distinct colour' is that two metals can emit different colours that are similar, but our eyes can't tell them apart. And also, the chemistry of metal cations in flame is not very well understood, and sometimes reactions can go unexpected depending on the composition of the flame/fuel/etc.