scn formal charge

Formal charge (FC) is a measure of the distribution of electrons in a molecule or ion. It is the difference between the number of valence electrons in an isolated atom and the number of electrons assigned to that atom in a molecule or ion. The formula for calculating formal charge is:

FC = valence electrons - (non-bonding electrons + 1/2 bonding electrons)

where valence electrons are the number of electrons in the outermost shell of the atom, non-bonding electrons are the number of electrons that are not involved in a chemical bond, and bonding electrons are the number of electrons shared between atoms in a chemical bond.

In the context of SCN-, the thiocyanate ion, the formal charges of each atom can be calculated as follows:

• S: Valence electrons = 6; Non-bonding electrons = 2; Bonding electrons = 2. Therefore, FC = 6 - (2 + 1) = +3
• C: Valence electrons = 4; Non-bonding electrons = 0; Bonding electrons = 3. Therefore, FC = 4 - (0 + 3/2) = 0.5
• N: Valence electrons = 5; Non-bonding electrons = 0; Bonding electrons = 1. Therefore, FC = 5 - (0 + 1/2) = +4.5

Overall, the formal charge of the SCN- ion is -1, which means that one extra electron is assigned to the entire ion.