link Buku :
1. web.ung.edu/media/Chemistry2/Chemistry-LR.pdf
2. web.ung.edu/media/chemistry/Chapter7/Chapter7-ChemicalBonding-MolecularGeometry.pdf
What is a covalent bond? What are some examples of molecules that contain covalent bonds?
Molecules that have covalent linkages include the inorganic substances hydrogen, nitrogen, chlorine, water, and ammonia (H2, N2, Cl2, H2O, NH3) together with all organic compounds
If one spares himself from being smart with MO Theory and confines only to the popular Valance Bond approach in perception, then we have sulfuric acid existing in the following canonic structures:
S there are totally 8 bonds, in all. 6 between S and O and 2 between O and H.
SO2 is a covalent compund !
Covalent compounds are formed when atoms share electrons to complete their octet.
Now, when two atoms that have similar electronegativities bond, the small difference between their respective electronegativities leads to a sharing of the bondingelectrons.
As you know, electronegativity gives you an idea about how good an atom is at attracting bonding electrons, which are electrons shared by two atoms when they form a chemical bond.
Now, sulfur and oxygen are both nonmetals, which means thay they have high electronegativity values when compared with metals.
So even if you don't know the exact electronegativities, you can always say that two nonmetals will form a covalent bond.
When a compound contains solely covalent bonds, then you can safely say that you're dealing with a covalent compound.
In this case, one way in which these three atoms bond will look like this
Sulfur shares a total of four valence electrons with the two oxygen atoms. Each oxygen atom shares two valence electrons with sulfur.
The three atoms will share a total of eight valence electrons, the equivalent of two double bonds.
There are other ways in which these three atoms can bond, you can read more on that here
http://socratic.org/questions/what-is-the-lewis-structure-for-so2
but all of them feature shared bonding electrons, which is the characteristic of a covalent compound.
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