Confused about magnesium's and calcium's emission spectra

In summary, magnesium's flame is white and emits all wavelengths of visible light, while calcium's flame is red/orange due to its valence electron requiring less energy to excite. However, the emission spectra of both elements show different wavelengths, with calcium appearing to emit blue and green light as well. This is due to the thermal emission of the burning metal, which is much stronger than the emission spectra. The emission spectra are influenced by both the excited valence electron and lower energy electrons.
  • #1
nucleon
2
0
I have read that magnesium’s flame is white, and the light emitted includes all the wavelengths of visible light. Calcium, on the other hand, needs less energy to excite its valence electron, and hence, during emission, the radiation given off has a longer wavelength (red light) and its flame is red/orange.

However, I got confused when I looked up the emission spectra for both:http://alexpetty.com/content/images/2014/09/Figure-12--The-light-signature-of-Magnesium.png%29,
http://alexpetty.com/content/images/2014/09/Figure-20--The-light-signature-of-Calcium.png
http://alexpetty.com/content/images/2014/09/Figure-12--The-light-signature-of-Magnesium.png
http://alexpetty.com/content/images/2014/09/Figure-12--The-light-signature-of-Magnesium.png%29,
Magnesium's spectrum shows less wavelengths than calcium's, which appears to emit also blue and green light (which have higher energy) at many more wavelengths. Based on these spectra, I would expect calcium to be the one to burn with a white flame...? Why is it still red/orange? And magnesium certainly does not appear to emit radiation at "all wavelengths of visible light"; I guess my book's wording is misleading?

Also, am I correct to say that elements show these different wavelengths because not only is the valence electron(s) excited when the substance is burned, for example, but also lower energy electrons => hence, we have different energy differences => radiation of different wavelengths is emitted?

All help is very much appreciated!
 
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  • #2
You are mistaking emission spectra of the elements with the thermal emission of the burning metal (or any substance burning as hot as magnesium).
 
  • #3
Aren't they related? Still a bit lost... Thank you for the response anyway!
 
  • #4
nucleon said:
Aren't they related?

In general - no.

Sure, as the heated element emits a bit on its own, its emission spectrum is present in the spectrum of the burning substance. But the thermal emission is - especially in the cases involved - much, much stronger.
 

1. What is an emission spectrum?

An emission spectrum is a pattern of lines or bands of light that are emitted by a substance when it is heated or excited. Each element or compound has a unique emission spectrum that can be used to identify it.

2. How are magnesium and calcium emission spectra different?

Magnesium and calcium have different emission spectra because they contain different numbers of electrons in their outermost energy levels. This results in different energy levels and transitions, leading to different wavelengths of light being emitted.

3. Why is magnesium's emission spectrum more complex than calcium's?

Magnesium's emission spectrum is more complex because it has more energy levels and electrons in its outermost energy level compared to calcium. This results in more transitions and a wider range of wavelengths being emitted.

4. How can emission spectra be used in scientific research?

Emission spectra can be used to identify and analyze elements and compounds in a sample. It can also be used to study the energy levels and electron configurations of atoms, which can provide valuable information about their properties and behavior.

5. What is the significance of understanding magnesium's and calcium's emission spectra?

Understanding the emission spectra of magnesium and calcium can help scientists in a variety of fields, such as astronomy, chemistry, and materials science. It can aid in the identification and analysis of these elements in different samples, as well as provide insights into their properties and behavior at the atomic level.

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