The correct option is **B. Covalent bond**. ### Detailed Explanation: 1. **Understanding Bond Types**: - **Ionic Bonds**: These bonds form when electrons are transferred from one atom to another, typically between a metal and a nonmetal. The metal loses electrons to become a positively charged ion (cation), while the nonmetal gains those electrons to become a negatively charged ion (anion). The electrostatic attraction between these oppositely charged ions creates an ionic bond. - **Covalent Bonds**: These bonds occur when two nonmetal atoms share one or more pairs of electrons. This sharing allows each atom to attain a stable electron configuration, often resembling that of noble gases. Covalent bonds can be single (one pair of shared electrons), double (two pairs), or triple (three pairs). - **Metallic Bonds**: These bonds are found in metals, where electrons are not shared or transferred but are instead delocalized over a lattice of metal cations. This "sea of electrons" allows metals to conduct electricity and heat and gives them their malleability and ductility. - **Hydrogen Bonds**: These are not true bonds but rather a type of intermolecular force that occurs when a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) is attracted to another electronegative atom. Hydrogen bonds are weaker than covalent and ionic bonds. 2. **Why Covalent Bonds Form Between Nonmetals**: - Nonmetals have high electronegativities, meaning they have a strong tendency to attract electrons. When two nonmetals come together, they can share electrons to fill their outer electron shells, achieving stability. For example, in a water molecule (H₂O), the oxygen atom shares electrons with two hydrogen atoms, forming covalent bonds. 3. **Why Other Options Are Incorrect**: - **A. Ionic Bond**: This option is incorrect because ionic bonds involve the transfer of electrons rather than sharing. They typically occur between metals and nonmetals, not between two nonmetals. - **C. Metallic Bond**: This option is incorrect because metallic bonds involve a lattice of metal cations surrounded by a sea of delocalized electrons. This type of bonding does not occur between nonmetals. - **D. Hydrogen Bond**: This option is incorrect because hydrogen bonds are a type of intermolecular force, not a bond formed between atoms in a molecule. They occur between molecules rather than within a single molecule. ### Example Calculation: While this question does not involve calculations, understanding the concept of bond formation can be illustrated with a simple example: - Consider the formation of a water molecule (H₂O): - Oxygen (O) has 6 valence electrons and needs 2 more to complete its octet. - Each hydrogen (H) atom has 1 valence electron and needs 1 more to complete its shell. - Oxygen shares one electron with each hydrogen atom, resulting in two covalent bonds. ### Common Pitfalls: - Confusing ionic and covalent bonds: Remember that ionic bonds involve electron transfer, while covalent bonds involve electron sharing. - Misunderstanding the nature of metallic bonds: Metallic bonds are not applicable to nonmetals and involve a different mechanism of electron behavior. ### Revision Summary: - **Covalent bonds** are formed by the sharing of electrons between two nonmetal atoms. - **Ionic bonds** involve electron transfer between metals and nonmetals. - **Metallic bonds** involve delocalized electrons in metals, not applicable to nonmetals. - **Hydrogen bonds** are intermolecular forces, not true bonds between atoms.