Textbook Question
Which type (or types) of crystalline solid is characterized by each of the following? (b) softness, relatively low melting point;
Ch.12 - Solids and Modern Materials
Chapter 12, Problem 15a,b,d,e,f
Indicate the type of solid (molecular, metallic, ionic, or covalent-network) for each compound: (a) CaSO4 (molecular, metallic, ionic, or covalent-network) for each compound: (b) Pd (molecular, metallic, ionic, or covalent-network) for each compound: (d) caffeine (C8H10N4O2) (molecular, metallic, ionic, or covalent-network) for each compound: (e) toluene (C7H8) (molecular, metallic, ionic, or covalent-network) for each compound: (f) P4.
Verified step by step guidance1
Step 1: Understand the types of solids. Molecular solids consist of molecules held together by intermolecular forces. Metallic solids are composed of metal atoms held together by metallic bonds. Ionic solids are formed from ions held together by ionic bonds. Covalent-network solids consist of atoms connected by covalent bonds in a continuous network.
Step 2: Analyze compound (a) CaSO4. Calcium sulfate is composed of calcium ions (Ca²⁺) and sulfate ions (SO₄²⁻). The electrostatic attraction between these ions forms an ionic solid.
Step 3: Analyze compound (b) Pd. Palladium is a metal, and its atoms are held together by metallic bonds, making it a metallic solid.
Step 4: Analyze compound (d) caffeine (C₈H₁₀N₄O₂). Caffeine is an organic molecule composed of covalently bonded atoms. It forms a molecular solid due to the presence of intermolecular forces between its molecules.
Step 5: Analyze compound (e) toluene (C₇H₈). Toluene is another organic molecule, similar to caffeine, and forms a molecular solid due to intermolecular forces between its molecules. Compound (f) P₄ is composed of phosphorus atoms covalently bonded in a discrete molecule, forming a molecular solid.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Types of Solids
Solids can be classified into four main types: molecular, metallic, ionic, and covalent-network. Molecular solids consist of molecules held together by intermolecular forces, while metallic solids are composed of metal atoms bonded by metallic bonds, allowing for conductivity. Ionic solids are formed from the electrostatic attraction between cations and anions, resulting in a crystalline structure. Covalent-network solids consist of a vast network of covalent bonds, leading to high melting points and hardness.
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Ionic Compounds
Ionic compounds are formed when metals transfer electrons to nonmetals, creating charged ions that attract each other. This type of bonding results in a lattice structure, which is characteristic of ionic solids. For example, calcium sulfate (CaSO4) is an ionic compound due to the presence of calcium ions (Ca²⁺) and sulfate ions (SO₄²⁻), which form a stable ionic lattice.
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Molecular Compounds
Molecular compounds are formed when two or more nonmetals share electrons through covalent bonds. These compounds typically have lower melting and boiling points compared to ionic compounds and exist as discrete molecules. For instance, caffeine (C8H10N4O2) and toluene (C7H8) are both molecular compounds, characterized by their specific molecular structures and weaker intermolecular forces compared to ionic or covalent-network solids.
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Related Practice
Textbook Question
Which type (or types) of crystalline solid is characterized by each of the following? (c) high melting point and poor electrical conductivity;
Textbook Question
Which type (or types) of crystalline solid is characterized by each of the following? (d) network of covalent bonds.
Textbook Question
Indicate the type of solid (molecular, metallic, ionic, or covalent-network) for each compound: (c) Ta2O5 (melting point, 1872°C)
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Textbook Question
You are given a gray substance that melts at 700 °C; the solid is a conductor of electricity and is insoluble in water. Which type of solid (molecular, metallic, covalent-network, or ionic) might this substance be?