Molecules vs Crystal Structures - Middle School Physical Science
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What is the key model feature of a metallic crystal?
What is the key model feature of a metallic crystal?
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Metal atoms in a lattice with delocalized electrons. Electrons move freely throughout the metal lattice.
Metal atoms in a lattice with delocalized electrons. Electrons move freely throughout the metal lattice.
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Which category best fits $CO_2$ in a particle model: molecule or extended crystal structure?
Which category best fits $CO_2$ in a particle model: molecule or extended crystal structure?
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Molecule. Carbon dioxide exists as separate $CO_2$ units.
Molecule. Carbon dioxide exists as separate $CO_2$ units.
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Which category best fits $O_2$ in a particle model: molecule or extended crystal structure?
Which category best fits $O_2$ in a particle model: molecule or extended crystal structure?
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Molecule. Oxygen gas consists of individual $O_2$ molecules.
Molecule. Oxygen gas consists of individual $O_2$ molecules.
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Which category best fits $NaCl$ in a particle model: molecule or extended crystal structure?
Which category best fits $NaCl$ in a particle model: molecule or extended crystal structure?
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Extended crystal structure (ionic crystal lattice). Salt forms a continuous lattice of alternating Na+ and Cl- ions.
Extended crystal structure (ionic crystal lattice). Salt forms a continuous lattice of alternating Na+ and Cl- ions.
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Which category best fits diamond (carbon) in a particle model: molecule or extended crystal structure?
Which category best fits diamond (carbon) in a particle model: molecule or extended crystal structure?
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Extended crystal structure (covalent network crystal). Each carbon bonds to 4 others in a continuous 3D network.
Extended crystal structure (covalent network crystal). Each carbon bonds to 4 others in a continuous 3D network.
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Which category best fits quartz ($SiO_2$) in a particle model: molecule or extended crystal structure?
Which category best fits quartz ($SiO_2$) in a particle model: molecule or extended crystal structure?
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Extended crystal structure (covalent network crystal). Silicon and oxygen form a continuous network structure.
Extended crystal structure (covalent network crystal). Silicon and oxygen form a continuous network structure.
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Identify the structure type: a model shows alternating $+$ and $-$ ions repeating in a 3D grid.
Identify the structure type: a model shows alternating $+$ and $-$ ions repeating in a 3D grid.
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Extended crystal structure (ionic crystal lattice). Alternating charges in 3D indicate an ionic crystal lattice.
Extended crystal structure (ionic crystal lattice). Alternating charges in 3D indicate an ionic crystal lattice.
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Identify the structure type: a model shows many identical triatomic groups separated from each other.
Identify the structure type: a model shows many identical triatomic groups separated from each other.
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Molecular substance (discrete molecules). Separated groups indicate individual molecules, not a lattice.
Molecular substance (discrete molecules). Separated groups indicate individual molecules, not a lattice.
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Identify the structure type: a model shows a continuous hexagonal sheet of atoms bonded throughout.
Identify the structure type: a model shows a continuous hexagonal sheet of atoms bonded throughout.
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Extended crystal structure (covalent network, like graphite layers). Continuous bonding throughout indicates a network crystal.
Extended crystal structure (covalent network, like graphite layers). Continuous bonding throughout indicates a network crystal.
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What is the meaning of “formula unit” in models of ionic crystals such as $NaCl$?
What is the meaning of “formula unit” in models of ionic crystals such as $NaCl$?
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Lowest whole-number ratio of ions in the crystal lattice. Shows the simplest ratio of ions, not an actual molecule.
Lowest whole-number ratio of ions in the crystal lattice. Shows the simplest ratio of ions, not an actual molecule.
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What is the key difference between a covalent network crystal and a molecular substance?
What is the key difference between a covalent network crystal and a molecular substance?
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Network: atoms bonded in a continuous lattice; molecular: discrete molecules. Networks form continuous structures; molecular substances have separate units.
Network: atoms bonded in a continuous lattice; molecular: discrete molecules. Networks form continuous structures; molecular substances have separate units.
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Which category best fits $H_2O$ in a particle model: molecule or extended crystal structure?
Which category best fits $H_2O$ in a particle model: molecule or extended crystal structure?
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Molecule. Water exists as individual $H_2O$ units, not a continuous lattice.
Molecule. Water exists as individual $H_2O$ units, not a continuous lattice.
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What is a unit cell in a crystal model?
What is a unit cell in a crystal model?
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Smallest repeating arrangement that builds the entire crystal. The unit cell repeats to form the entire crystal structure.
Smallest repeating arrangement that builds the entire crystal. The unit cell repeats to form the entire crystal structure.
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What is the key difference between an ionic crystal model and a molecular model?
What is the key difference between an ionic crystal model and a molecular model?
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Ionic crystal: alternating ions in a lattice; molecular: separate molecules. Ionic crystals have continuous lattices; molecular substances have distinct units.
Ionic crystal: alternating ions in a lattice; molecular: separate molecules. Ionic crystals have continuous lattices; molecular substances have distinct units.
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What is the defining feature of a molecule model compared with a crystal model?
What is the defining feature of a molecule model compared with a crystal model?
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Molecule: discrete unit; crystal: repeating lattice extending in 3D. Molecules are individual units; crystals have infinite repeating patterns.
Molecule: discrete unit; crystal: repeating lattice extending in 3D. Molecules are individual units; crystals have infinite repeating patterns.
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What term describes a substance made of separate, individual groups of bonded atoms?
What term describes a substance made of separate, individual groups of bonded atoms?
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Molecular substance (made of discrete molecules). Molecules exist as separate, independent units of bonded atoms.
Molecular substance (made of discrete molecules). Molecules exist as separate, independent units of bonded atoms.
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What term describes a solid made of a repeating pattern of particles throughout the solid?
What term describes a solid made of a repeating pattern of particles throughout the solid?
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Crystal (extended structure with a repeating lattice). Crystals have particles arranged in regular, repeating 3D patterns.
Crystal (extended structure with a repeating lattice). Crystals have particles arranged in regular, repeating 3D patterns.
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Which option best indicates a model represents a crystal: identical units repeat in all directions or one unit stands alone?
Which option best indicates a model represents a crystal: identical units repeat in all directions or one unit stands alone?
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Identical units repeat in all directions. Crystals show repetition; molecules are standalone units.
Identical units repeat in all directions. Crystals show repetition; molecules are standalone units.
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Which option best indicates a model represents a molecule: repeating lattice or a single bonded cluster?
Which option best indicates a model represents a molecule: repeating lattice or a single bonded cluster?
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A single bonded cluster (one discrete unit). Molecules exist as individual, separate units.
A single bonded cluster (one discrete unit). Molecules exist as individual, separate units.
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Identify the structure from a model showing identical groups of $3$ atoms repeated but not connected to each other.
Identify the structure from a model showing identical groups of $3$ atoms repeated but not connected to each other.
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Molecular substance (separate molecules). Groups not connected indicate individual molecules.
Molecular substance (separate molecules). Groups not connected indicate individual molecules.
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Identify the structure from a model showing alternating $+$ and $-$ ions in a repeating grid pattern.
Identify the structure from a model showing alternating $+$ and $-$ ions in a repeating grid pattern.
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Ionic crystal (extended lattice). Alternating charges in a grid show continuous ionic bonding.
Ionic crystal (extended lattice). Alternating charges in a grid show continuous ionic bonding.
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Which option best describes a molecular model: one continuous network or separate identical units?
Which option best describes a molecular model: one continuous network or separate identical units?
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Separate identical units (individual molecules). Molecules maintain their identity as separate entities.
Separate identical units (individual molecules). Molecules maintain their identity as separate entities.
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Which option best describes a crystal model: particles arranged randomly or in a repeating pattern?
Which option best describes a crystal model: particles arranged randomly or in a repeating pattern?
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Particles arranged in a repeating pattern. Crystal structures have ordered, predictable arrangements.
Particles arranged in a repeating pattern. Crystal structures have ordered, predictable arrangements.
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What type of attraction usually holds ions together in an ionic crystal lattice?
What type of attraction usually holds ions together in an ionic crystal lattice?
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Electrostatic attraction between oppositely charged ions. Positive and negative charges attract throughout the crystal.
Electrostatic attraction between oppositely charged ions. Positive and negative charges attract throughout the crystal.
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What type of bonding usually holds atoms together within a molecule?
What type of bonding usually holds atoms together within a molecule?
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Covalent bonding. Atoms share electrons to form strong bonds within molecules.
Covalent bonding. Atoms share electrons to form strong bonds within molecules.
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