Question

What is Lewis structure?

Answer 1

Lewis structure can easily be drawn if we know the molecular formula of the compound. It can also be referred to as Electron dot structure or Lewis dot structure. So, to make lewis structure we have to find the molecular formula of the compound and then we can move ahead.

Complete step by step answer:
A Lewis structure is a very simple way to represent the valence shell electrons of a molecule. It gives an idea on how the electrons are paired/arranged around an atom in the molecule.
In Lewis dot structure, each electron can be represented in the form of dots and for bonding the electrons a line is drawn that connects the dots.
While drawing Lewis dot structure, we ignore the electrons which do not belong to the outermost shell and only the valence electrons are considered.
Steps for drawing Lewis structure:
-Calculate the total number of valence electrons present in a molecule (sum of all the valencies of every atoms)
-For anionic molecule, add some extra electrons (Extra electron= magnitude of negative change).
-For Cationic molecules, subtract the electron from total as a makeup for the positive charge.
-Choose the least electronegative atom as the central atom of the molecule.
-Now the atoms will get connected using a single bond.
-Assign each atom with the lone pairs of electrons belonging to the molecule. The most electronegative atom is assigned with the lone pair first.
-Satisfy the octet valency of each atom, if required draw double or triple bonds.
-To satisfy the octet rule of two atoms, sometimes a lone pair is converted into a bond pair.

Note:
The Lewis structure is the most limited and simplest theory, it does not explain how the bonds are formed or how the electrons are shared in between the atoms. And this is considered to be the basic limitation of Lewis structure.