Slides in this set
The electronegativity of an atom is a measure of its tendency to attract electron pairs from
· If an atom has a high electronegativity it attracts electrons more easily.
· Pauling's Electronegativity measures electronegativity, this isn't given in exams so it is important
to learn the trends.
Increasing by 0.5
Increasing by 0.3 (approx.)
· As you go down a group, electronegativity decreases because number of shells increase
therefore outer shell is further away from nucleus this results in less attraction between nucleus
and electrons thus it is harder to attract an electron.
· As you go across a period, electronegativity increases because there are more positive protons
in the nucleus for a given number of shells, therefore it is easier to attract a negatively charged
· Alkali Metals and other metals have very low electronegativity. Therefore they fail to
keep there outer electrons for long.
· The outer electron therefore becomes delocalised.
· Resulting in Cat ions surrounded by a sea of delocalised electrons.
· When atoms have electronegativity of less than 1.9
We have low
and our electrons
just choose to
stay away from
· The more outer electrons of a metal, the more delocalised
electrons, this results in stronger bonds between the cat
ions and delocalised electrons.…read more
· Pure covalent bonds are formed when an atom with an electronegativity of more than 1.9
joins with another atom with less than 0.5 difference in electronegativity. As the electrons
would be distributed evenly between the two atoms.
· Due to similar electronegativity, electrons are attracted to both rather than
one over the other.
· This equal distribution forms a pure covalent bond…read more
Polar Covalent Bonding
· Polar covalent bonds are formed when an atom with an electronegativity of more than
1.9 joins with another atom with more than 0.5 but less than 2.0 difference in
· The electrons would not be distributed evenly between the two atoms but there would
not be a complete transfer in electrons, therefore a dipole is formed.…read more
· Ionic bonds only exists in theory, In reality all bonds are covalent(ish).
Delta + Delta -
Very Low Very High electronegativity
electronegativity (0.9) (3)
· The atom with the very high electronegativity attracts the electron from the other atom.
The electron prefers to stay closer to the atom with the high electronegativity. This is
known as a complete transfer of electrons.
· Ionic bonds are formed when there is a difference of at least 2.1 between the two atoms.…read more