Electronegativity and electron affinity is often confused to be the same thing. The two are indeed correlated and one can loosely use the two terms interchangeably but neither literally nor technically are the two identical. Hence, the two terms or the concepts are not exactly inter-replaceable or interchangeable.
Explained: Electronegativity and Electron Affinity?
Electrons are continuously moving from one atom to another atom. This is a very common phenomenon. An electron detaches itself from one atom and is transferred to another atom. The quantum of energy that is released when this electron is transferred to an atom is electron affinity. If you think about it, there is a release of energy when the atom accepts or gains the electron so there should be some energy generation or required to detach the electron from the original atom.
Energy is neither created nor destroyed in this process. It is merely transferred from one form to another or causes the transfer. The amount of energy needed to detach the electron from the original atom may be exactly as the amount of energy released hence the energy needed can also be described as electron affinity.
Electronegativity is the energy or the quantum of molecular ability to share an electron between two atoms courtesy a covalent bond. It is not necessary for an electron to be transferred to another atom for it to receive or gain the electron. Two atoms in a molecule can share an electron through a covalent bond. This energy or molecular ability to form the covalent bond and share an electron is electronegativity.
Difference Between Electronegativity and Electron Affinity
Electron affinity can be calculated. It is quantifiable value. Using certain scientific means immediately after the transfer of an electron and when an atom gains or attaches the electron to itself you can infer the energy required or released. Electronegativity cannot be calculated. You cannot quantify the value or molecular capability when an electron is shared by two atoms forming a covalent bond.
It is known that the higher a molecule’s electronegativity, the stronger is the covalent bond but there is no scientific way of figuring this out in sheer numbers or value. Electronegativity values may and will vary depending on the specific molecule that the electron is bonded to.
Electronegativity pertains to molecules and not every atom. Electron affinity is a definitive value for every individual atom. Due to the lack of one universally agreed approach to calculate electronegativity, there are many ways and none of them have consensus. Also, electronegativity varies given the circumstances or chemical environments.
