chemistry 2.5 - electronegativity and polarisation

What is electronegativity?

The ability of n atom to attract the handing electrons in a covalent bond

What is electronegativity measured with?

The Pauling scale, highest = 4.0 (fluorine), lowest = 0.7

What makes electronegativity higher?

Higher nuclear charge and smaller atomic radius

What does it mean if the atoms have a similar electronegativity?

That the binding electrons will be midway between the nuclei = non polar bond

What does it mean if the atoms have a difference in electronegativity?

Usually it has to be a difference bigger than 0.4 and it means the atom with the higher electronegativity will pull the bonding electrons closer to it making it partially negative whilst the other atom will be partially positive = polar bond

What is a dipole?

A difference in charge between 2 atoms caused by a shift in electron density in the bond

What happens in a polar bond?

The electronegativity difference causes a dipole

What are purely covalent bonds?

Electronegativity is 0 so electrons arranged completely evenly (only in bonds of single element e.g. O-O)

Why do some compounds have covalent and ionic properties?

Because they are between completely covalent and completely ionic due to their difference in electronegativity

How can you use electronegativity to predict the bonding between 2 atoms?

Higher difference = more ionic

Where can you find the electronegativity of elements and what percentage ionic character relates to electronegativity difference?

In the data book given

What are polar molecules?

Molecules with an overall dipole (caused by presence of a permanent charge across the molecules)- contain polar bonds that aren’t symmetrical