Electronegativity & Electronegativity Difference Supplemental Notes printable pdf download

Electronegativity & Electronegativity Difference Supplemental Notes

What is electronegativity

We have a name for the amount of pull that one atom exerts on the electrons that it is

sharing with other atoms. It is called electronegativity.

Definition ~Electronegativity is a measure of the tendency of an atom to attract a

bonding pair of electrons. Fluorine (the most electronegative element) is assigned a

value of 4.1, and values range down to cesium and francium which are the least

electronegative at 0.86.

Patterns of electronegativity in the Periodic Table

The most electronegative element is fluorine. If you remember that fact,

everything becomes easy, because electronegativity must always increase

towards fluorine in the Periodic Table.

Note: This simplification ignores the noble gases. Historically this is because

they were believed not to form bonds - and if they don't form bonds, they can't

have an electronegativity value. Even now that we know that some of them do

form bonds, data sources still don't quote electronegativity values for them.

Trends in electronegativity across a period

As you go across a period the electronegativity

increases. The chart shows electronegativities from

sodium to chlorine - you have to ignore argon. It

doesn't have an electronegativity, because it doesn't

form bonds.

Trends in electronegativity down a group

As you go down a group,

electronegativity decreases. (If it

increases up to fluorine, it must

decrease as you go down.) The chart

shows the patterns of electronegativity

in Groups 1 and 7.

Explaining the patterns in electronegativity

The attraction that a bonding pair of electrons feels for a particular nucleus

depends on:



the number of protons in the nucleus;



the distance from the nucleus;



the amount of shielding by inner core electrons.

All rights Jim Clark

and Eden Francis

Electronegativity & Electronegativity Difference Supplemental Notes