Question

While making the lewis structure of NO3- we make it normally but while making the lewis structure for H2SO4 we consider the formal charge of the sulphur the central atom to be zero then the structure is completed.. Why like this? in the lewis structure of NO3- is not zero still the structure is correct but in H2SO4 after putting all the electrons correctly then we check the formal charge to be zero then only our structure is completed.. why?

Answer 1

Lewis diagrams are to be used to examine mechanisms so that knowing which parts of a molecule are electron deficient and which are electron rich are vital. It is ideal to have a formal charge of 0 for as many of the atoms as possible. If a formal charge of 1- is located next to a formal charge of $1+$ , the formal charges can be minimized by having a lone pair of electrons, located on the atom with the 1-charge become a bonding pair of electrons that is shared with the atom that has the $1+$ formal charge (this can be visualized in the same way as the formation of multiple bonds were above).

Structures 1 and 2 are resonance structures of each other, but structure 2 is the lower energy structure, even though it violates the octet rule. Sulfur can accommodate more than eight electrons, and the formal charges in structure 2 are all zero.