Chemical Bonding and Charge Concepts

In the perchlorate ion (ClO4-), there are four equivalent oxygen atoms sharing a single negative charge delocalized over the entire ion, meaning the effective charge on each oxygen atom is -1/4. In sulfite (SO3 2-), the charge per oxygen is -2/3, and in chlorate (ClO3-), it is -1/3.

In the bisulphate ion (HSO4-), the sulphur atom is bonded to four oxygen atoms. One oxygen is bonded to hydrogen, and the others are double-bonded or single-bonded with negative charges to satisfy the octet rule, resulting in a formal charge of +2 on the central sulphur atom.

Formula change is basically a change given to an atom, on assuming that the electrons in a chemical bond are shared equally between the atoms, neglecting theirrelative, $EN.$

In the nitrate ion (NO3-), the nitrogen atom is at the center bonded to three oxygen atoms. Using the formal charge formula, nitrogen has 5 valence electrons, 0 lone pair electrons, and 8 bonding electrons (4 bonds), resulting in 5 - 0 - 4 = +1.

Formal charge$=$Valence electrons-non bonding electrons+no of bonds$ =6-(4+2)=0$

In the cyanide ion the formal negative charge resonates between $C$ and $N$. Cyanide ion has resonating structure, $-\overset { \ _ }{ C } \equiv N\longleftrightarrow \overset { \ _ }{ N } \underrightarrow { = } C$

formal charge= valence electrons-(lone electrons+bonds)
$=7-(2+3)=+2$