Chemical bonds hold atoms together in compounds. The three main types are ionic, covalent, and metallic bonds, each with distinct properties.
Ionic bonds form when one atom transfers electrons to another, creating oppositely charged ions that attract. For example, sodium (Na) loses one electron to become Na⁺, and chlorine (Cl) gains one electron to become Cl⁻, forming NaCl (table salt). Ionic compounds typically form crystalline solids with high melting points.
Covalent bonds form when atoms share electron pairs. A single bond shares one pair, a double bond shares two pairs, and a triple bond shares three pairs. Water (H₂O) has two single covalent bonds. Covalent compounds tend to have lower melting points and can exist as gases, liquids, or soft solids.
Polar covalent bonds share electrons unequally, creating partial charges. Nonpolar covalent bonds share electrons equally. The polarity of bonds determines many physical properties like solubility and boiling point.