Formal charge: kind of confused?
why cant i get -1? i just want to know if the way im solving it, if its completely wrong. i have a test soon. please help!
tinypic
. com
/view.php?pic=14buuti&s=7
ok in class we did this.
and for O FC= 6-4-3=+1
but S FC = -1 (I get 6-4-1= +1) which is wrong. what am i doing wrong?
i solve by doing: group # - total (bonds and lone pairs(each = 1)) - lone pairs (each pair = 1)
Sorry but that url doesn't help me. I get nothing although I do get a tiny pic page.
I don't use this "formula" method because it takes me longer to classify group #, bonds, and lone pairs than to count. Here is how you can count them.
http://www.google.com/images?q=lewis+structure+SO2&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&source=univ&ei=GjlYTe65GsT0gAeGrL2EDQ&sa=X&oi=image_result_group&ct=title&resnum=2&ved=0CCsQsAQwAQ&biw=791&bih=398
Count electrons around an atom as follows:
1 each for unshared electrons. Electrons shared between atoms--give half of the electrons in the bond to each atom. The formal charge is then What it should have - what it has. For H2O,
  ..
H:O:
..
H
So H has 1 electon, it should have 1, FC = 0
Other H is the same.
O. We have 2 electrons at the top and two on the right side (total now 4) + 1 electron for 1 H -O bond and 1 for the other H-O bond which makes 6. It should have 6. FC = 0
To determine the formal charge on an atom, you can follow the method you've described: subtract the number of electrons assigned to an atom in a molecule from the number of valence electrons that atom normally has. However, it seems like you are missing a crucial step in your calculation, which is assigning the correct number of electrons to each atom.
According to the image you provided, the oxygen atom (O) is bonded to two other atoms and has two lone pairs of electrons. Therefore, the oxygen atom has 4 electrons from the bonds (2 bonds x 2 electrons per bond) and 4 electrons from the lone pairs (2 lone pairs x 2 electrons per pair). This gives a total of 8 electrons assigned to the oxygen atom.
Using this information, let's calculate the formal charge for oxygen (O):
Formal Charge (O) = Valence Electrons (O) - Total Electrons Assigned to O
Now, the valence electrons for oxygen (O) is 6.
Formal Charge (O) = 6 - 8 = -2
So the formal charge on the oxygen atom is -2, not +1 as you calculated previously. It seems like you might have made a mistake in counting the electrons assigned to the oxygen atom.
As for the sulfur atom (S) in the image, it has 6 valence electrons. Again, you need to count the total number of electrons assigned to sulfur to find its formal charge. However, I can't access the image you provided to see the arrangement of bonds and lone pairs on the sulfur atom, so I can't assist you further with finding its formal charge.
Remember to carefully count the number of electrons assigned to each atom when calculating formal charges, and you should be able to determine the correct formal charges for the atoms in a molecule.