What is electronegativity and how does it affect bonding?

Electronegativity is an atom's ability to attract shared electrons in a bond. It influences bond type and polarity. When two atoms with similar electronegativity bond, electrons are shared equally, forming a non-polar covalent bond (e.g., O₂). If there's a moderate difference, the bond is polar covalent (e.g., H₂O). A large difference results in an ionic bond (e.g., NaCl). Electronegativity increases across a period and decreases down a group in the periodic table. Fluorine is the most electronegative element. Bond polarity affects solubility, reactivity, and physical properties of compounds.