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Polarisation and electronegativity
12 December 2012
18:13

- Bonds between atoms of a single element, e
...
Diatomic gases, H2 or O2 can be purely covalent
- Very few compounds are close to purely ionic

- Electronegativity- the ability to attract the bonding electrons
in a covalent bond
- Measured using Pauling's scale
- Fluorine is the most electronegative
- Electronegativity increases across periods and decreases
down a group
- The covalent bond between two atoms of different
electronegativity-> the bonding electrons are pulled towards
the more electronegative atom making the bond polar

- Covalent bonds in dipolar atoms have equal electronegativity making them non-polar
- Bonds between different atoms with similar electronegativities are non-polar eg
...
HCl- polar bond gives overall permanent dipole
- Complex molecule eg
...

- If polarised enough, it can become covalent with a dipole making it a polar molecule

Increasing positive charge- more polarised
anion
Na+

Cl-

Mg2+

Cl-

Al3+

- More covalent bond is polarised--> the more ionic character it gains
- More ionic bond is polarised--> the more covalent character it gains

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