Electronegativity is the ability of a bonded atom to attract the pair of electrons in a covalent bond.The Pauling scale used is from 0 - 4. Electronegativity decreases down the
group.
Because of their high electronegativities they are
oxidising agents and are able to gain electrons to form negative ions. Electronegativity decreases because:
•nuclear charge - the bigger the nuclear charge the higher the electronegativity
• the distance between the nucleus and bonding pair of electrons. The shorter the distance the higher the electronegativity.
•the fewer the energy levels the smaller the
shielding effect therefore the higher the electronegativity
| element | electronegativity |
| fluorine | 4.0 |
| chlorine | 3.0 |
| bromine | 2.8 |
| iodine | 2.5 |
| astatine | 2.2 |