- Steel is classified as metallic because it conducts electricity in solid and liquid states due to delocalized electrons.
- Propane is classified as covalent due to its low melting point, characteristic of weak intermolecular forces in molecular substances.
- Calcium chloride is ionic because it conducts electricity in aqueous solutions, showing it dissociates into ions.
- Water is classified as covalent as a molecular substance with a low melting point.
Explanation
- Analysis of Bonding Types
The classification of substances based on their bonding types relies on understanding how electrons interact between atoms.
- Metallic bonds involve a "sea of delocalized electrons" that are free to move throughout the structure. This movement of charge allows materials to conduct electricity in both solid and liquid states. Steel is an alloy of iron and carbon, exhibiting these characteristics, which makes it a metallic substance.
- Covalent bonds occur when atoms share electrons to achieve stable electron configurations. These typically form discrete molecules with relatively weak intermolecular forces, which explains why compounds like Propane (\(C_3H_8\)) and Water (\(H_2O\)) have low melting points.
- Ionic bonds are formed by the electrostatic attraction between oppositely charged ions. These substances usually have high melting points and, when dissolved in a solvent like water, the crystal lattice dissociates into free-moving ions. This movement of ions allows the solution to conduct electricity, which is the property observed for Calcium chloride (\(CaCl_2\)).
- Classification of Substances
Based on the properties provided, we can systematically classify each substance:
- Steel: Conducts electricity as a solid and a liquid. This is the defining characteristic of metallic bonding, where electrons are free to move.
- Propane: Has a low melting point. This is characteristic of small, nonpolar or weakly polar covalent molecules held together by weak intermolecular forces.
- Calcium chloride: Conducts electricity when dissolved in water. This indicates the substance dissociates into ions (\(Ca^{2+}\) and \(Cl^-\)), which is a primary feature of ionic compounds.
- Water: Melts at \(0^{\circ}\text{C}\) and is a brittle solid (in ice form). These properties are indicative of covalent molecular solids, which are held together by hydrogen bonds (a type of intermolecular interaction) rather than strong ionic or metallic bonds. Thus, water is classified as having covalent bonds.
- Conclusion
The final classification is:
Steel: \(\text{Metallic}\)
Propane: \(\text{Covalent}\)
Calcium chloride: \(\text{Ionic}\)
Water: \(\text{Covalent}\)
Examples
Understanding bonding types is crucial for material science and engineering. For instance, engineers choose metals like steel for structural frames because metallic bonds provide high strength and conductivity. Conversely, knowing that propane has covalent bonds helps engineers design storage systems for fuel, as they know it will exist as a gas or liquid at relatively low temperatures and pressures compared to ionic salts. Understanding these properties helps in everything from choosing the right cookware to designing advanced electrical circuits.