A covalent bond is a type of chemical bond where two atoms share one or more pairs of electrons. This sharing allows each atom to achieve a more stable electron configuration, similar to that of noble gases. Covalent bonds typically form between nonmetal atoms, such as in molecules like water (H₂O) and carbon dioxide (CO₂). Covalent compounds can exist as gases, liquids, or solids, depending on their molecular structure and intermolecular forces. These compounds often have distinct properties, such as lower melting and boiling points compared to ionic compounds. Examples of covalent substances include methane (CH₄) and sucrose (C₁₂H₂₂O₁₁).