Aug. 15th, 2014

Three quantum numbers.

n, the principal quantum number
l, the angular momentum quantum number
m, the magnetic momentum quantum number


n has positive integers as its possible values
l has 0...n - 1 as its possible values
m has -l to +l as its possible values
spin has -1/2 and +1/2

l = 0 is aliased as s
l = 1 is aliased as p
l = 2 is aliased as d
l = 3 is aliased as f

So if n = 1, l must be 0, and m must be 0. Only one possibility.

If n = 2, l can be 0 or 1, and m can be -1, 0, or +1.
n = 2, l = 0, m = 0
n = 2, l = 1, m = -1
n = 2, l = 1, m = 0
n = 2, l = 1, m = +1


you can have as many orbitals in a subshell as combinations of quantum numbers
2 electrons per orbital (spin?)
Pauli exclusion principle says you can't have two electrons with the same quantum numbers

orbitals have different shapes
some are spherical
some are have lobes shaped like teardrops
these are statistical tendencies for electrons to be found
not uniform density within the orbital
some places are zero probability

We have shells, subshells, and orbitals. 2 elecrons to an orbital. Many orbitals to a subshell (as many as possible values of m * 2). Each shell corresponds to an n value.

If all subshells are filled, you have a noble gas. If you can fill a subshell or empty it, that's a stable configuration. = noble gas core.

Ionic is when one atom loses an electron and another gains it. Then they have opposite charges and attract.

Covalent is when they share electrons. Sigma and pi bonds depending on the shape of the orbitals and how much they overlap. Shorter bonds are stronger because the electrons are closer to both nuclei.

Metallic is when the electrons move around freely. This is why metals are good conductors. Covalent bonds that permit a lot of freedom of movement mimic metallic bonds.

van der Waals bonds are when the electrons move around, and that creates a week magnetic bond. Graphite is made of sheets held weakly together because the electrons on average are on one side or the other of the sheet, but at a given moment one side of the sheet or other has a positive or negative charge.

Graphite molecules are held together in sheets with shorter and stronger bonds that diamond.

different polyhedra

Silicon tetrahedron: silicon cation (cations are smaller because they have a positive charge, fewer electrons, and the fewer electrons mean smaller atom) in the middle, squeezed between 4 oxygen anions in a tetrahedron. Each silicon shares an electron with one oxygen. Each silicon tetrahedron can potentially share oxygen ions with 1, 2, 3, or 4 tetrahedra in pairs, chains, rings, sheets, and 3D frameworks.


gap between energy levels explains color
wavelengths

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