Re: Does electronegativity effect electroconductivity of an element?Why?

Dear John,

Electroconductivity is totally unrelated to electronegativity. First of all electronegativity has meaning only when an atom forms a molecular bond with a dissimilar element. Electroconductivity refers to a bulk property of an element or a compound.

Atoms on the top right-hand side of the periodic table are the most electronegative, while atoms on the bottom left-hand side are electropositive. As you move from left to right along the periodic table, the elements become more electronegative because they are gaining protons in their nuclei.

Let's take a look at water for a minute. Water contains three atoms, 2 hydrogen atoms and an oxygen atom. While oxygen has 6 electrons and 6 protons, each hydrogen has only one electron and one proton. Each atom has a balance of charges, but valence electrons are shared between the three atoms. Oxygen is said to be more electronegative than hydrogen, because those 6 protons at its nucleus represent a densely packed concentration of positive charge. Hydrogen's single electron is shared with oxygen, but the electron is drawn away from hydrogen's nucleus towards the oxygen. As you go down the periodic table, elements gain still more protons. However, each shell of electrons added to the element shields the underlying nucleus with a layer of negative charge.

In a bulk material, whether it be composed of atoms of similar or dissimilar atoms, valence electrons are the glue that holds the whole mass together. The stronger the bonds between those atoms, the more tightly bound the electrons will be to those atoms. In conductive materials, some electrons are able to free themselves and leap frog around the bulk material, replacing other electrons along the way. Metals like copper are not only conductive, but also malleable (or "bendable"). This is because the atoms of the metal are weakly held together and can "mush" around to take on a new shape. Ceramic materials are strong insulators and comparatively fragile. What doesn't bend, breaks.

To go into more detail, conductivity is measured by the difference between the valence and the conduction bands of the bulk material. If you are familiar with bonding and anti-bonding orbitals of molecular bonds, you can think of valence and conduction bands as the bonding and anti-bonding orbitals for the bulk material. A simple illustration of this is the hydrogen-hydrogen bond of hydrogen gas (H2). The two electrons are in constant motion in, around, and through the two atoms. The compound is at it's most stable (lowest energy) state when the two electrons are equally shared between the two nuclei. This is the bonding orbital. The compound would be least stable when the two electrons are on opposite sides of each nuclei from one another. The latter example is referred to as an anti-bonding orbital because the protons would be face to face and their mutual positive charges would repel one another, breaking the molecule apart. Just like molecular bonds are a composite of all their constituent atomic bonds, valence and conduction bands are a combination of bonding and antibonding orbitals of all the constituent bonds holding the bulk material together. The weaker those bonds (i.e. the smaller the difference in energy between the valence and conduction bands) the easier it is to displace an electron and allow it to migrate through the material.

Good luck,

Marc