Periodic Table

The ground state configuration of atoms can be constructed using the four quantum numbers. The shells are designated by capital letters:

The angular momentum sub shells are given lower case letters:

s (=0), p(=1), d(=2), f(=3), g( =4), h( =5), ...

Each s-sub shell can have two electrons in it (One with spin up, and one with spin down).

Each p-sub shell can have 6 electrons in it. (There are 3 different m numbers possible: -1, 0, 1, and each of them can be occupied by two electrons, one with spin up, and one with spin down.)

For the same reasoning, each d-sub shell can have 10 electrons in it. In general, for each value of , we can have 2(2+1) electrons occupying this particular angular momentum sub shell.

The electronic configurations of the first eighteen elements are shown below. For each electronic configuration, one first lists the n quantum number, then the angular momentum subshell, and then the occupation of that subshell - denoted by an exponent, if that sub shell is occupied by more than 1 electron. For example, the notation "1s² 2s" means that the n=1 shell has its s-sub shell filled with two electrons, and that the n=2 shell has one electron in its s-sub shell.

Electrons in closed shells or sub shells are tightly bound and do not normally undergo chemical or electrical phenomena. Closed shell atoms are the noble gases helium, neon, argon, krypton, xenon, and radon. Atoms with one electron outside a closed shell are called alkali metals, lithium, sodium, ... . Atoms with one electron missing from a closed shell are called halides, fluorine, chlorine, ... .

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