Formal charges on CH2O and H2SO3
I was taught thus way valence electrons subtracted from addition of dots plus bonds
For CH2O
Carbon 4-(0+3) = + 1
. Oxygen 6-(4+1) = - 1
For H2SO3 I am having issues figuring out the dots and bonds
I think you're having trouble with the CH2O, too. I think by your formula and the way I do it that the formal charge on C is 0 and the formal charge on O is 0. (and the formal charge on each H is 0).
Here is the dot structure.
http://www.thegeoexchange.org/chemistry/bonding/Lewis-Structures/CH2O-lewis-structure.html
The way you've been taught is
For C. valence e = 4
- additional dots = 0
- bonds and there are 4 (1 CH, another CH and 2 for C=O making 4)
so 4-4 = 0
The way I do it.
valence e = 4
1e from the CH bond belongs to C; ( that's 1)
1e from the other CH bond belongs to C(that's 2)
There are 4 electrons shared with the C=O and half of them belong to C.(That's 2 more to make a total of 4)
So C should have 4, it has 4, charge zero.
To determine the formal charges on the atoms in H2SO3, we need to follow the same method you mentioned.
For H2SO3:
Hydrogen: Each hydrogen atom has 1 valence electron. In this case, each hydrogen atom forms a single bond with sulfur, which provides an additional electron. So, hydrogen has a formal charge of 0.
Sulfur: Sulfur has 6 valence electrons. In H2SO3, there are 3 pairs of electrons (6 electrons) forming bonds with hydrogen. Sulfur also has 2 lone pairs of electrons. Considering the total number of valence electrons, the formal charge on sulfur can be calculated as: 6 - (2 + 1 + 1) = +2. So, sulfur has a formal charge of +2.
Oxygen: Each oxygen atom has 6 valence electrons. In H2SO3, there are 3 oxygen atoms. Each oxygen atom forms one double bond with sulfur and has one lone pair of electrons. Considering the total number of valence electrons, the formal charge on oxygen can be calculated as: 6 - (2 + 2 + 1) = +1. So, each oxygen atom has a formal charge of +1.
By following this method, we can determine the formal charges on each atom in CH2O and H2SO3.
To determine the formal charges on the atoms in a molecule, you can use the following formula:
Formal charge = (Number of valence electrons on the atom) - (Number of lone pair electrons) - (Number of shared electrons)
Let's first determine the formal charges on each atom in CH2O:
Carbon (C):
Valence electrons: 4
Lone pair electrons: 0 (no lone pairs indicated)
Shared electrons: 3 bonds (each bond has 2 electrons)
Formal charge = 4 - 0 - 6 = -2
Hydrogen (H):
Valence electrons: 1
Lone pair electrons: 0 (no lone pairs indicated)
Shared electrons: 1 bond (each bond has 2 electrons)
Formal charge = 1 - 0 - 2 = -1 (for each H atom)
Oxygen (O):
Valence electrons: 6
Lone pair electrons: 2 (indicated by two pairs of dots)
Shared electrons: 2 bonds (each bond has 2 electrons)
Formal charge = 6 - 2 - 4 = 0
So the formal charges for CH2O are:
Carbon: +1
Hydrogen: -1 (for each H atom)
Oxygen: 0
Now let's determine the formal charges for H2SO3:
Hydrogen (H):
Valence electrons: 1
Lone pair electrons: 0 (no lone pairs indicated)
Shared electrons: 1 bond (each bond has 2 electrons)
Formal charge = 1 - 0 - 2 = -1 (for each H atom)
Sulfur (S):
Valence electrons: 6
Lone pair electrons: 0 (no lone pairs indicated)
Shared electrons: ??
To determine the shared electrons for sulfur (S), we need to look at the Lewis structure or molecular formula of H2SO3. Based on the formula, H2SO3 consists of one sulfur atom (S) bonded to two hydrogen atoms (H) and two oxygen atoms (O). The bonds between sulfur and hydrogen (S-H) contribute to the shared electrons on sulfur. Since sulfur forms two bonds with hydrogen, it will have a total of 4 shared electrons.
Formal charge on sulfur (S):
Valence electrons: 6
Lone pair electrons: 0 (no lone pairs indicated)
Shared electrons: 4 (two S-H bonds)
Formal charge = 6 - 0 - 4 = +2
Oxygen (O):
Valence electrons: 6
Lone pair electrons: 2 (indicated by two pairs of dots)
Shared electrons: ??
Similar to sulfur, we need to determine the number of shared electrons on oxygen (O) by looking at the Lewis structure or molecular formula of H2SO3. Each oxygen atom in H2SO3 is bonded to the sulfur atom (S) and has a lone pair of electrons. Therefore, the shared electrons for each oxygen atom will be the total number of bonds it forms.
Formal charge on oxygen (O):
Valence electrons: 6
Lone pair electrons: 2 (indicated by two pairs of dots)
Shared electrons: 2 (one S-O bond)
Formal charge = 6 - 2 - 2 = +2 (for each O atom)
So the formal charges for H2SO3 are:
Hydrogen: -1 (for each H atom)
Sulfur: +2
Oxygen: +2 (for each O atom)