[ruhker]

Hello, I am having a hard time in my Chemistry class, and that's why I am taking remedials this coming Tuesday, and even after reading our book, General Chemistry 7th edition by Whitten, Stanley, Davis and Peck, I still couldn't understand fully..

I have now my ideas on polarity, but I am still not sure..

-so, uhm.. how do I really know whether if the bonds are polar or non-polar? What is it to cancel? Polar have lone pairs right and non-polars don't have? But, is it possible for polars to not have lone pairs right? Can you give me examples.

-How do I know about how short or long the bond angles are?

- What is a dipole moment? Two polars, right? Can you give me example?

- Am I correct on these?
... it is considered polar if the electronegativity is zero?
... if the electronegativity is high, it is ionic?

Sorry for posting rather easy questions for you.. hehe, I just don't understand some of the lessons.. And thanks in advance for those who can help me understand polarity and bonds better. 

[DevaDevil]

the terms polar and non-polar bonds are (almost) always used in covalent bonds. not ionic. even a high electronegativity difference (as in C-F bond) is covalent

The property of a bond that determines the polarity is the difference in electronegativity between the bonding atoms. If the difference is (decently) big, it's a polar bond. So a difference in electronegativity of 0 mans a NON-Polar bond.
Lone pairs are not part of the principle of a polar bond.

The dipole moment is the vector you obtain by the summation of the vectors of all the polar bonds in a compound. So a compound with different polar bonds can have no dipole moment. This is true in the case of mirror-symmetric molecules, which have no permanent dipole moment. (the vectors cancel each other out)

Most bond angles are geometry - specific. You should know them for the basic geometries. find more about those here

[ruhker]

Thank you,

Uhm, another ones.. hehe.

What is the difference between polar or nonpolar BOND from polar or nonpolar MOLECULE? Are they the same to obtain?

[mmetecaliskan]

no they are different
one molecule  contains polar bonds but it can be non polar molecule
such as methane
all bonds (C-H)  are polar but molecule is non polar
to understand the molecule is polar or not you can think the bonds as a vector
if the sum of the vectors is zero it means this molecule is non polar if not ; polar