Molecular Polarity

Molecular Polarity

In chemical bonds, polarity refers to an uneven distribution of electron pairs between the two bonded atoms—in this case, one of the atoms is slightly more negative than the other. But molecules can be polar too, and when they are polar, they are called dipoles. Dipoles are molecules that have a slightly positive charge on one end and a slightly negative charge on the other. Look at the water molecule. The two lone electron pairs on the oxygen atom establish a negative pole on this bent molecule, while the bound hydrogen atoms constitute a positive pole. In fact, this polarity of water accounts for most of water’s unique physical properties. However, molecules can also contain polar bonds and not be polar. Carbon dioxide is a perfect example. Both of the C—O bonds in carbon dioxide are polar, but they’re oriented such that they cancel each other out, and the molecule itself is not polar.

Assessment (Post your answer using the Stoplearn.com box below for evaluation and discussion)

These are factors which determine whether a molecule is polar or non-polar except

1. shape of the molecule
2. number of lone pairs in an atom
3. number of electronegative elements present
4. polarity of covalent bond

These are examples of unit cell cubic structure

1. simple cubic structure
2. non-linear cubic structure
3. face-centered cubic structure
4. body centered cubic structure

These are intermolecular bonds or attractions except

1. metallic bond
2. dipole – dipole attractions
3. van-der Waal’s forces
4. hydrogen bond

List the properties of simple molecular substances