Electronegativity, Chemistry, OCR A, As Level

Notes on Electronegativity

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ELECTRONEGATIVITY
Electronegativity is a measure of the ability of an atom to attract the pair of electrons in
a covalent bond.
Electronegativity depends upon the size of the nuclear charge: it is the force of
attraction between the nuclear charge and the pair of electrons that `pulls' the electrons
towards an atom.
The size of the atom is also important: as the size of an atom decreases the nucleus is
closer to the shared pair of electrons in the covalent bond and hence the nuclear charge
is more effective.
Going across a period, the nuclear charge increases and the size of the atom decreases.
This results in an increase in electronegativity.
Going down a group, the value of electronegativity decreases since the atoms
increase in size and the effect of the increased nuclear charge is offset by the shielding
of the extra inner electrons.
Most electronegative element if Fluorine (non-metal)
Least electronegative element is Francium (metal)
The type of bonding depends upon the difference in electronegativity.
No difference in electronegativity (or very similar values) results in non-polar
covalent bonds in which the pair of electrons is equally shared
Difference in electronegativity results in polar covalent bonds in which the pair
of electrons is not equally shared: this results in partial charges on the atoms
and a permanent dipole
As the difference in electronegativity increases the bonds become more polar.
A very large difference in electronegativity results in ionic bonding

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johnny zhang

nice resource, concise and to the point just what i needed :)

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