Polar bonds and electronegativity

What is electronegativity?

The power of an atom to attract the bonding pair of electrons in a covalent bond.

What is the trend for electronegativity across a period?

It increases left to right, with fluorine being the most electronegative.

What is the trend for electronegativity along a group?

It increases up a group.

What does it mean for an atom to be delta positive?

Electrons are pulled more to the end of an atom making it slightly positive.

What does it mean for an atom to be delta negative?

Electrons are pulled more to the end of an atom making it slightly negative.

What is a permenant dipole?

The difference in charge between two atoms involved in a covalent bond due to the attraction of the electron pair by the more electronegative atom.

How are electrons in a polar molecule distributed?

Asymmetrically, causing a permenant dipole.

How are electrons in a non-polar molecule distributed?

Symmetrically, with no permenant dipole.

The bond between the atoms is pure covalent.

How can you make predictions that an atom is going to be polar?

-Molecules with symmetrical shapes tend to be polar

-Molecules with OH, H and N at the end tend to be non-polar

How can you predict when a molecule is going to be non-polar?

-Molecules containing carbon tend to be non-polar.

-Diatomic elements tend to be non-polar.

What are the features of non-polar molecules?

-Contain no polar bonds

-Contain some polar bonds but the delta charges cancel each other out so no permenant dipole is formed.

What are the features of polar molecules?

-Contain asymmetrical polar bonds