Trying to determine if a molecule is polar or nonpolar

[dnt]

1) when trying to determine if a molecule is polar or nonpolar, how do unpaired electrons and double bonds affect it? for example, in CO3 (2-), its trigonal planar but one of the C=O bonds is a double bond...is this polar or nonpolar?

2) what do you do when you have an odd number of electrons and you want to draw the lewis structure?

3) when naming compounds, when do you use the di, tri, tetra prefixes? for example, P205 is diphosphorous pentaoxide, but BaCl2 is not barium dichloride but rather barium chloride only.

4) when talking about quantum numbers, how do you know when an atom is in its ground state? the question i have is regarding a valence electron in a K atom in its ground state and the quantum number choices are (n,l,m,s): (a) 3,0,0,1/2 (b) 3,1,1,1/2 (c) 4,0,0,1/2 (d) 4,1,1,1/2 and (e) 4,2,1,1/2

i thought the first principal quantum number (n) tells the energy state but from there i don't know which to choose.

another example is the quantum number for a valence electron with greatest energy in a P atom in ground state. again, the choices are (a) 2,0,0,1/2 (b) 2,0,1,1/2 (c) 2,1,0,1/2 (d) 3,1,1,1/2 and (e) 3,2,1,1/2

again, doesn't the first number tell us about the energy? so I am assuming the 2nd problem (P atom) is between d and e but from there i don't know which one.

thanks.

 

[Astronuc]

1) With regard to molecular geometry - http://www.up.ac.za/academic/chem/mol_geom/mol_geometry.htm
http://www.chem.uncc.edu/faculty/murphy/1251/slides/C19a/

2) Try these with respect to the Lewis structure.

http://en.wikipedia.org/wiki/Lewis_Structure
http://www.chemtutor.com/compoun.htm#lewis
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/lewis.html#c1

3) With regard to naming compounds, International Union of Pure and Applied Chemistry (IUPAC) establishes conventions for nomenclature.

I think P₂O₅ is also called phosphorus pentaoxide, and there is also P₂O₃ or phosphorus trioxide (or phosphorus (III) oxide). I would think most introductory chemistry textbooks would have an explanation of the nomenclature.

4) K is an akali metal, so has 1 s electron in the valence shell. K begins Period number: 4. The s electron can only have l = 0 and therefore m=0, and that leave 1/2 for the electron spin.

Phosphorus is in group 3.

Here is a nice general reference on the periodic table - http://www.webelements.com/ .

http://hyperphysics.phy-astr.gsu.edu/hbase/atpro.html

All the quantum numbers have something to do with energy, but the biggest factor is the principal quantum number, while the others involve the angular momentum, and interactions with magnetic fields.

http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/hydrad.html#c3

http://hyperphysics.phy-astr.gsu.edu/hbase/qunoh.html#c2

http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/qnenergy.html#c1

http://hyperphysics.phy-astr.gsu.edu/hbase/atomic/atstruct.html#c1