How can emission spectra used to identify presence of specific elements in a substance?

Answer 1

In atomic spectroscopy, each element has a unique spectrum. The atomic spectrum obtained from a sample is a combination of the spectra of each elemental component. We take the strongest line from the sample spectrum and determine which elements could have caused it (we call these "candidates"). We then look at the full spectrum from each candidate and see whether or not every major line is present in the sample spectrum. If so, we say that element is present.

Then we subtract the spectrum (or spectra) of the element(s) we have determined to be present from the sample spectrum and repeat the same process with the next strongest line in the (leftover) sample spectrum. We continue repeating this process until all lines in the sample spectrum are accounted for.

Answer 2

Elements can either emit light of a specific colour (sodium lights are yellow) or absorb light of a specific colour thus, assuming you are looking at an absorption spectrum, if you look carefully at the spectrum you will see dark bands in it. The pattern of these bands is unique to each element and therefore reveals the presence of the element at the source of the light, or between the source of the light and the observer.

Answer 3

The spectrum of an unknown substance can be compared to known spectra. The idea is that each element has its characteristic spectrum - sometimes this is compared to an element's "fingerprint".

The other trick is that the pattern (characteristic spectrum) may be shifted, e.g., towards the lower wavelengths, and yet it is the same substance.

Answer 4

Each chemical element has specific emission or absorption spectra. Spectral analysis is widely used in analytical chemistry.

Answer 5

Each element has a specific emission spectra.

Answer 6

Atomic emission spectra are chracteristic for each element.