how do we know whether a compound is polar or non polar?how?

Asked by gnikhilvarma | 31st May, 2009, 06:32: PM

Expert Answer:

A compound is polar if it has some dipole moment and is non- polar if it has no dipole moment.

To know whether a compound is polar or non - polar, compare the electronegativities of the atoms forming the bond.

Always remember that two different atoms will have different electronegativities.

If there is an electronegativity difference between the atoms forming the bonds, the molecule is non- polar. Take an example of H-Cl and Cl-Cl.

In H-Cl the two atoms forming the bonds are H and Cl. Both have difefrent electronegativities. So, the molecule HCl will be polar molecule.

Now, the next molecule is Cl-Cl. Both the atoms are Cl. there is no electronegativity difference. So ,it will be non- polar.

If a molecule involves more than one bonds, polarity will also depend on the shape along with the dipole moment.

In CCl4 , there are four C-Cl bonds . So ,the C-Cl bond will be polar but the molecule will be non- polar because the shape is tetrahedral and the molecule is symmetrical. SImilarly, CO2 will be non- polar since it conatins same C=O bonds and the shape is linear.

So, to summarise, First check how many difefrent types of bonds the molecule has, number of bonds , shape of the molecule.



Answered by  | 2nd Jun, 2009, 02:31: PM

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