HELP with chemistry homework: what is a electron shell?

Question

What in the world is an electron shell? I'm supposed to find how many of them are in a magnesium atom, but I don't even know what they are! Please help, will give best answer.

Answer 1

here u go

http://en.wikipedia.org/wiki/Electron_shell

Answer 2

In atomic physics, an electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. Electron shells are made up of one or more electron subshells, or sublevels, which have two or more orbitals with the same angular momentum quantum number l. Electron shells make up the electron configuration of an atom. It can be shown that the number of electrons that can reside in a shell is equal to 2n2.

The existence of electron shells was first observed experimentally in Charles Barkla's and Henry Moseley's X-ray absorption studies. Barkla labelled them with the letters K, L, M, etc. (The origin of this terminology was alphabetic. K and L were originally called B and A, but were later renamed to leave room for hypothetical spectral lines that were never discovered.) These letters were later found to correspond to the n-values 1, 2, 3, etc. They are used in the spectroscopic Siegbahn notation.

The name for electron shells originates from the Bohr model, in which groups of electrons were believed to orbit the nucleus at certain distances, so that their orbits formed "shells".

Answer 3

hi Nancy With atomic nujmber 9 it quite is a fluorine atom. In its un excited so referred to as "floor state" it has 2 electrons interior the 1st potential point and 7 electrons interior the 2d potential point. yet you will see that interior the electron association of two, 6 and a million, that between the electrons interior the 2d potential point has moved as much as the 0.33 potential point, information of the addition of potential to the atom it quite is named an "excited state. this may be very unusual for fluorine because it has an exceedingly good charm for the seven electrons in its ;2d potential point by way of fact it is so small and very near to ending up a so referred to as good Octet of electrons by employing gaining one extra electron in its outer point if it may from yet another atom.l

Answer 4

answer:
4 shells
1s2 2s2 2p6 3s2

Answer 5

Hope this helps
http://en.wikipedia.org/wiki/Electron_shell