Questions and Answers
Graphite is a type of ______ network solid made up of carbon atoms.
covalent
Diamond and graphite are examples of ______ of carbon.
allotropes
Molecular solids are held together by ______ forces.
intermolecular
Most molecular solids are ______, while those with permanent dipoles are polar.
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Molecular solids generally have ______ melting points compared to ionic solids.
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Sodium chloride (NaCl) is an example of an ______ solid.
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Most covalent network solids have ______ conductivity, except for graphite.
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The ability of a single element to form multiple structures is known as ______.
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Crystalline solids are classified according to the type of forces that hold its particles together, including metallic, covalent network, molecular, and ______.
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Metallic solids consist entirely of ______ atoms.
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Metallic bonding involves a uniform distribution of atomic nuclei within a 'sea' of ______.
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Covalent network solids are poor conductors and are typically characterized by strength, hardness, and high ______ points.
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Covalent network solids are characterized by a network of ______ bonds that extend throughout the material.
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Diamond is made up of carbon atoms and is known as the hardest ______ material.
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Metallic solids consist of positively charged ions surrounded by a sea of ______.
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Molecular solids possess distinct ______ forces, such as Van der Waals forces or hydrogen bonding.
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Molecular solids are usually characterized by ______ melting points compared to covalent network solids.
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Allotropes are different forms of an element, an example of which is that diamond is an allotrope of ______.
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Allotropy refers to the existence of an element in more than one ______ form.
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Some properties of metallic solids include high electrical and thermal conductivity, being malleable, and ______.
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The types of crystals include ionic, covalent, molecular, and ______ solids.
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In a crystalline solid, the arrangement of ions or atoms creates a ______ structure.
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The unit cell is the smallest repeating unit of a crystal structure that defines its ______ properties.
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A crystal lattice represents the arrangement of ______ points in the unit cell.
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Study Notes
Crystalline Solids Overview
- Crystalline solids are organized in a repeating pattern, held by strong intermolecular forces.
- Classification based on bonding types: metallic, covalent network, molecular, and ionic.
Covalent Network Solids
- Consist of atoms bonded by a network of covalent bonds.
- Examples: graphite (2D, good conductor) and diamond (3D, hardest known material, thermal conductor).
- Graphite forms flat sheets and is an allotrope of carbon, while diamond is renowned for its hardness.
Molecular Solids
- Comprised of covalently bonded atoms/molecules, held by intermolecular forces (e.g., van der Waals).
- Generally insulators, soft, and melting points vary significantly (e.g., ice: 0°C, sugar: 186°C, fullerene: 280°C).
- Polar molecules, like sugar, have higher melting points and are soluble in water.
Ionic Solids
- Made of cations (positive ions) and anions (negative ions), bonded through electrostatic attractions.
- Difficult to break and typically have high melting points, exemplified by sodium chloride (NaCl).
Metallic Solids
- Composed entirely of metal atoms with metallic bonding, characterized by a "sea" of delocalized electrons.
- Features include high electrical and thermal conductivity, malleability, ductility, and variable melting points.
- Examples include sodium and copper, which exhibit close-packed atomic arrangements.
Allotropy
- Refers to the ability of a single element to form multiple structural forms.
- Carbon has notable allotropes: diamond and graphite, each with unique properties.
Unit Cell Concepts
- The unit cell is the smallest repeating unit of a crystalline solid, defining the crystal structure.
- Crystal lattices and motifs are used to visually represent these structures.
- In 2D, a unit cell is typically a parallelogram; in 3D, it is a parallelepiped, with variations based on lattice points.
Lattice Structures
- 2D lattices have four primitive types: square, rectangular, hexagonal, and oblique.
- 3D lattices feature seven primitive types: cubic, hexagonal, tetragonal, rhombohedral, orthorhombic, monoclinic, and triclinic.
- Specific cubic lattices include primitive (lattice points at corners), body-centered (extra point at center), and face-centered (extra point at the center of faces).
Summary of Properties
- Covalent network solids are generally strong with high melting points but poor conductors (exception: graphite).
- Molecular solids exhibit variability in melting points and are typically insulators.
- Ionic solids are strong and have high melting points.
- Metallic solids are conductive with malleability and ductility, suitable for various applications.
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Description
Test your knowledge on different types of crystalline solids, focusing on covalent network solids such as graphite. This quiz will cover the allotropy of elements and the properties of various solid structures. Prepare to explore the fascinating world of crystalline materials and their unique characteristics.
