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 dont 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, doesnt the first number tell us about the energy? so im assuming the 2nd problem (P atom) is between d and e but from there i dont know which one. thanks.