Questions and Answers
Which of the following characteristics would you expect for a solid with the formula P₄?
Given an unknown substance with a melting point of 962 °C, insoluble in water, and conducts electricity as a solid, which of the following could be its identity? Check all that apply.
Given an unknown substance with a melting point of 872 °C, soluble in water, and does not conduct heat as a solid, which of the following could be its identity? Check all that apply.
Why do molecular solids differ greatly in their hardness and melting points?
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What kinds of attractive forces may exist between particles in molecular crystals?
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What kinds of attractive forces exist between particles in covalent-network crystals?
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What kinds of attractive forces exist between particles in ionic crystals?
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What kinds of attractive forces exist between particles in metallic crystals?
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Indicate the type of crystal for CaCO₃.
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Indicate the type of crystal for Pt.
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Indicate the type of crystal for ZrO₂ (melting point, 2677°C).
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Indicate the type of crystal for Table sugar (C₁₂H₂₂O₁₁).
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Indicate the type of solid for benzoic acid, C₆H₅COOH.
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Indicate the type of solid for I₂.
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Which type of solid might a white substance be if it sublimes at 3000°C, is a nonconductor of electricity, and is insoluble in water?
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Which type of solid might a substance be if it melts with some decomposition at 730 °C, is a nonconductor of electricity, but dissolves in water to form a conducting solution?
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Is Si a molecular, metallic, ionic, or covalent-network solid?
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Is SiO₂ most likely a molecular, metallic, ionic, or covalent-network solid?
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Study Notes
Classification of Types of Solids
- P₄ is characterized by poor thermal conductivity and low melting point but not by high electrical conductivity or hardness.
- A substance with a melting point of 962 °C, insoluble in water, that conducts electricity as a solid and is hard could possibly be silver (Ag).
- A substance with a melting point of 872 °C, soluble in water, that does not conduct heat as a solid and is hard may be zinc fluoride (ZnF₂).
- Hardness and melting point differences between types of solids are attributed to molecular interactions; molecular solids have weak intermolecular forces.
Types of Attractive Forces
- Molecular crystals can exhibit:
- London dispersion forces
- Hydrogen bonding
- Dipole-dipole forces
- Covalent-network crystals are held together by covalent chemical bonds.
- Ionic crystals feature electrostatic or coulombic forces between particles.
- Metallic crystals have metallic bonds that hold their particles together.
Types of Crystals
- Calcium carbonate (CaCO₃) is identified as an ionic crystal.
- Platinum (Pt) is classified as a metallic crystal.
- Zirconium dioxide (ZrO₂), with a melting point of 2677 °C, is an ionic crystal.
- Table sugar (C₁₂H₂₂O₁₁) is categorized as a molecular crystal.
- Benzoic acid (C₆H₅COOH) is also classified as a molecular solid.
- Iodine (I₂) is recognized as a molecular crystal.
Special Cases
- A white substance that sublimes at 3000 °C, is a nonconductor of electricity, and is insoluble in water is likely a covalent-network solid.
- A white substance that melts with some decomposition at 730 °C, nonconductive in solid form but forms a conducting solution in water, suggests it is an ionic solid.
- Silicon (Si) is classified as a covalent-network solid.
- Silicon dioxide (SiO₂) is another example of a covalent-network solid, known for its hardness and insolubility in water.
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Description
Explore the various classifications of solids, including their properties and types of attractive forces that hold them together. This quiz covers characteristics of molecular, ionic, metallic, and covalent-network crystals. Test your understanding of how these different solids behave under various conditions.
