Can someone please give me a brief overview of emission spectroscopy?

Question

I am studying analytical techniques at the moment in senior chemistry and I am having trouble trying to understand emission spectroscopy. Information on chemical theory, its application and just a brief overview would really help. Please Help!

Answer 1

Neils Bohr advanced his theory of the atom as a miniature "solar system", where electrons orbit the nucleus like planets orbit the Sun. Imagine if you jumped from Mars to Earth, this would be a "downhill" jump since you are landing closer to the Sun's gravity. Doing so requires you to lose energy, and in the case of the Bohr model of the atom, such a jump will give off a specific amount of energy in the form of a specific sized photon. Jumping from Jupiter to Mars will give off another sized photon, and jumping from Jupiter to Earth will give off another sized photon, etc.etc. The total zoo of all possible sized photons is referred to as the emission spectrum, and if you excite the electrons in a certain sample they will then give off this collection of different sized photons. These are called Fraunhoffer lines, after the German guy who first described them. Each "collection of photons" is unique for each kind of atom, just as would also be true between two different solar systems, (Alpha Centauri would be different from us, for instance). So if you don't know what something is, you can do an emission spectrum on it and find that it is made of.....say Aluminum and Sulfur, for instance, based on the exact energies of the collection of photons emitted. I hope this helps.