SL Chem - Unit #1: Electronegativity

Electronegativity

The ability for an atom to attract and hold onto electrons

Electronegativity trend on the periodic table

On the periodic table it electronegativity increases by going up diagonally towards the top right (Uses the Pauling Scale)

Electronegativity trends going down the group

It decreases down a group

• This is because of a greater shielding affect and lower affective nuclear charge making the valence electrons more loosely held and easier to rid of (rather than attracting electrons)

Electronegativity trends going across the period (to the right)

It increases as we go across the row

• Because more protons in the nucleus creates a stronger effective nuclear charge that attracts and holds onto electrons a lot better

Electronegativity for Noble Gases

Noble gasses are stable elements (already have a full valence shell) that don’t attract any electrons so they have no electronegativity value

Diatomic

Elements that can self stabilize by creating covalent bonds with themselves to create a stable shell

• HOFBrINCl

Monoatomic

An element that is naturally found on it’s own because it’s already stable and doesn’t need to bond with anything else to stabilize

• All Noble Gases

Pauling Scale

Is the scale that measures the strength of bonds between covalent bonds

• Despite being derived from physical quantities (the bonds energy) the electronegativity number itself have no value, they are just used for comparative ways among themselves

Electrostatic Charge

The interaction that between a covalent bond that helps hold them together

Electronegativity Difference In Ionic Bonds

ΔEn ≥ 1.7

• The electron is fully transferred between atoms making the dipole moment either ±

Electronegativity Difference In Polar Covalent Bonds

0.5 ≤ ΔEn < 1.7

Electronegativity Difference In Non-Polar Covalent Bonds

0 < ΔEn < 0.5

Non-Polar Covalent

The electron is equally shared between both elements and it’s located in the middles

• No dipole Moment

Polar Covalent

The electron is shared unbalanced between the two, the atom with the higher electronegativity pulls the electron towards itself more than the other

• It has partial dipole movement

  • Slight negative end: “δ− “

  • Slightly positive end: “δ+”

Which End is δ− / δ+

the element that has a higher electronegativity is the δ- end of the bond