Dear nitin,
Lewis Structures for Covalent Compounds
- In a covalent compound, electrons are shared between atoms to form a covalent bond in order that each atom in the compound has a share in the number of electrons required to provide a stable, Noble Gas, electronic configuration.
- Electrons in the Lewis Structure (electron dot diagram) are paired to show the bonding pair of electrons.
- Often the shared pair of electrons forming the covalent bond is circled
- Sometimes the bond itself is shown (-), these structures can be referred to as valence structures.
Examples
hydrogen fluoride, HF
- Hydrogen atom has 1 valence electron
- Fluorine atom has 7 valence electrons
- Hydrogen will share its electron with fluorine to form a bonding pair of electrons (covalent bond) so that the hydrogen atom has a share in 2 valence electrons (electronic configuration of helium) and fluorine has a share in 8 valence electrons (electronic configuration of neon)
- Lewis Structure (electron dot diagram) for hydrogen fluoride
OR
- Valence Structure for hydrogen fluoride
ammonia, NH3
- Nitrogen atom has 5 valence electrons
- Hydrogen atom has 1 valence electron
- Each of the 3 hydrogen atoms will share its electron with nitrogen to form a bonding pair of electrons (covalent bond) so that each hydrogen atom has a share in 2 valence electrons (electronic configuration of helium) and the nitrogen has a share in 8 valence electrons (electron configuration of neon)
- Lewis Structure (electron dot diagram) for ammonia
OR 
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All the best.
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