The sum of oxidation numbers in an uncharged molecule will be 0.
For example, H2O has O2- and 2H+.
1(-2) + 2(+1)=0
The sum of oxidation numbers in a charged species will equal the charge.
For example, HCO3- has H+, C4+, and 3O2-.
1(+1) + 1(+4) + 3(-2) = -1
For a neutral molecule it is zero, for polyatomic ions the sum is the same as the ionic charge.
The oxidation number of I in I2O5 is +5, because oxygen has an oxidation number of -2 and the overall charge of the molecule is 0. The sum of the oxidation numbers in a molecule must equal the overall charge of the molecule.
The oxidation number of nitrogen in NH4+ is -3. The overall molecule h2n-coonh4 is neutral, so the total sum of oxidation numbers will be zero. Therefore, the oxidation number of nitrogen in this molecule is -3.
The sum of the oxidation numbers of all the atoms in C6H5CHO is equal to zero. This is because in a neutral molecule like C6H5CHO, the total oxidation number must balance out to zero.
In SO2, the oxidation number for sulfur is +4 and for each oxygen is -2. The sum of the oxidation numbers of all atoms in SO2 will be zero since it is a neutral molecule.
For a neutral molecule it is zero, for polyatomic ions the sum is the same as the ionic charge.
The oxidation number of I in I2O5 is +5, because oxygen has an oxidation number of -2 and the overall charge of the molecule is 0. The sum of the oxidation numbers in a molecule must equal the overall charge of the molecule.
The oxidation number of nitrogen in NH4+ is -3. The overall molecule h2n-coonh4 is neutral, so the total sum of oxidation numbers will be zero. Therefore, the oxidation number of nitrogen in this molecule is -3.
The sum of the oxidation numbers of all the atoms in C6H5CHO is equal to zero. This is because in a neutral molecule like C6H5CHO, the total oxidation number must balance out to zero.
In SO2, the oxidation number for sulfur is +4 and for each oxygen is -2. The sum of the oxidation numbers of all atoms in SO2 will be zero since it is a neutral molecule.
The oxidation number of Mn in Mn(ClO4)3 is +7. Each Cl has an oxidation state of -1 and each O has an oxidation state of -2. The sum of the oxidation numbers should equal the charge of the molecule, which is 0 in this case.
The oxidation number of Mn in Mn2O7 is +7. This is because oxygen normally has an oxidation number of -2, and since the molecule is neutral, the sum of the oxidation numbers must equal zero.
The sum of oxidation numbers in a neutral compound is always zero, as the charges balance out. In polyatomic ions, the sum of oxidation numbers equals the charge of the ion. When determining oxidation numbers, rules such as assigning elements in their elemental state an oxidation number of zero and hydrogen an oxidation number of +1 are typically followed.
The oxidation number of carbon in ethane (C2H6) is -3. This is because hydrogen is assigned an oxidation number of +1, and since the molecule is neutral, the sum of the oxidation numbers must be zero.
P3+
The oxidation number for carbon in CH3F is -3, for hydrogen it is +1, and for fluorine it is -1. The sum of the oxidation numbers must equal the overall charge of the molecule, which in this case is 0.
The sum of the oxidation numbers for P2O5 is zero. In P2O5, the oxidation number for phosphorus is +5, and each oxygen atom has an oxidation number of -2. Since there are five oxygen atoms, the total sum of the oxidation numbers is 2(+5) + 5(-2) = 0.