Electronegativity is the tendency of an atom to attract shared electrons (or electron density) towards itself when it forms a chemical bond with another atom. It essentially measures how strongly an atom pulls on the bonding electrons in a molecule
. Key points about electronegativity:
- It is influenced by the atomic number (number of protons) and the distance of the valence electrons from the nucleus. Atoms with more protons and smaller atomic radius tend to have higher electronegativity because the nucleus exerts a stronger pull on the electrons
- The most commonly used scale to quantify electronegativity is the Pauling scale, where fluorine is the most electronegative element with a value of 4.0, and elements like cesium and francium have very low values around 0.7
- Electronegativity generally increases across a period from left to right on the periodic table and decreases down a group. This is because atoms gain more protons and have smaller radii across a period, increasing attraction for electrons, while adding electron shells down a group increases distance and shielding, reducing attraction
- The difference in electronegativity between two bonded atoms determines the bond type: large differences lead to ionic bonds, moderate differences to polar covalent bonds, and small or no difference to nonpolar covalent bonds
In summary, electronegativity reflects how strongly an atom attracts electrons in a bond, influencing molecular polarity and chemical bonding behavior
