Electronegativity

Electronegativity is a measure of how strnogly an atom in a molecule rejects extra electrons away from itself. This occurs because an atom has a positively charged centre (made up of protons and neutrons) which is continuously orbited by electrons. Outside electrons are rejected because the charge distribution of an atom can be thought of as a positive centre surrounded by negativity. This negativity rejects any outside electrons (which also have a negative charge). Electronegativity increases as the number of electrons and orbital shells around the nucleus increases; they shield the outside electrons from the postive nucleus, which attacts them, making their rejection easier.