On the basis of the description given classify each of the following solids as molecular, metallic, ionic, or covalent network. Explain why?
A. a lustrous, yellow solid that conducts electricity
B. a hard, black solid melting at 2350 degrees C to give a nonconducting liquid
C. a nonconducting, pink solid melting at 650 degrees C to give an electrically conducting liquid
D. red crystals having a characteristic odor and melting at 171 degrees C
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To classify each solid, we need to analyze their properties and determine the type of bonding present.
A. A lustrous, yellow solid that conducts electricity: This solid is likely a metal. Metals are known for being lustrous and conducting electricity due to the presence of freely moving electrons in the metallic bonding. The positive metal ions are held together in a lattice structure by a sea of delocalized electrons.
B. A hard, black solid melting at 2350 degrees C to give a nonconducting liquid: This description points towards a covalent network solid. Covalent network solids are typically made up of a network of covalent bonds extending throughout the entire solid structure. These bonds are strong, resulting in high melting points. Since the liquid formed after melting does not conduct electricity, it suggests that there are no mobile charged particles to carry electric current, which is a characteristic of covalent network solids.
C. A nonconducting, pink solid melting at 650 degrees C to give an electrically conducting liquid: This solid undergoes a change in conductivity upon melting, which suggests the presence of ionic bonding. Ionic compounds consist of a lattice of positive and negative ions held together by electrostatic forces. In the solid state, the ions are fixed in place and cannot conduct electricity. However, upon melting, the ions become mobile and can carry electric current, resulting in the liquid state being electrically conducting.
D. Red crystals having a characteristic odor and melting at 171 degrees C: Based on the given description, this solid is likely a molecular solid. Molecular solids are made up of discrete molecules held together by weaker intermolecular forces, such as van der Waals forces or hydrogen bonds. The presence of a distinctive odor suggests the presence of molecules that can vaporize and be detected by the nose. Additionally, the relatively low melting point indicates weak forces between the molecules.
In summary:
A. Metallic solid
B. Covalent network solid
C. Ionic solid
D. Molecular solid