Electronegativity and Polarity

6.2

Define electronegativity

Electronegativity is the ability of an atom to attract the bonding electrons in a covalent bond to itself

What are the most electronegative atoms

1. Fluorine

2. Oxygen

3. Chlorine

How is electronegativity measured

Electronegativity is measured using the Pauling electronegativity values

What factors affect electronegativity and how

1. Nuclear charge- higher = higher E.N

2. Atomic radius- smaller = higher E.N

3. Shielding- more = lower E.N

What happens to electronegativity ACROSS a period and why

Electronegativity increases because:

1. Nuclear charge increases

2. Atomic radius decreases

What happens to electronegativity DOWN a group

Electronegativity decreases because:

1. Shielding increases

2. Atomic radius increases

3. Nuclear charge increases but this is outweighed by other 2 factors

When does a non-polar bond form

1. A bond is non polar when:

   1. bonding atoms are same OR

   2. bonding atoms have same/similar E.N

What makes a bond non-polar

Non-polar bond forms when the bonded electron pair is shared EQUALLY between the bonded atoms

What is a pure covalent bond

A pure covalent bond is one with a small E.N difference

What makes a bond polar

Polar bond forms when the bonded electron pair is NOT shared EQUALLY between the bonded atoms

What type of dipole is in a polar covalent bond

A permanent dipole

Will a symmetrical molecule ever be polar

Why

No because the individual dipoles will cancel out