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Chapter 12 - Solids and Modern Materials

Classifying solids based on bonds

  • Metallic solids - Held together by a sea of collectively shared electrons.

  • Ionic solids - Sets of cations and anions mutually attracted to one another.

  • Covalent-network solids - Joined by an extensive network of covalent bonds.

  • Molecular solids - Discrete molecules held together by weak forces.

Types of solids

  • Polymers - Contain a long chain of atoms connected by covalent bonds. They have different properties than small molecules or metallic ionic compounds.

  • Nanomaterials - Crystalline compounds with the crystals on the order of 1-100nm. They have different properties than larger crystalline materials.

  • Crystalline - Solids with a repeating pattern of atoms.

  • Amorphous - Lack of order in the arranged atoms.

Unit Cell

  • Unit cell - The basis of a repeating pattern.

  • The structure of a crystalline solid is defined by

    • Size and shape of unit cell

    • Location of atoms in the unit cell

  • Crystal lattice - Geometric pattern on which the unit cell is.

  • Lattice points - Positions that define the overall structure of the crystalline compound.

    • Each point has an identical environment.

Basic 3D lattices

  • Cubic

  • Tetragonal

  • Orthorhombic

  • Rhombohedral

  • Hexagonal

  • Monoclinic

  • Triclinic


  • Centered lattices - Have atoms in another regular location, most common in the body center (body-centered) or center of the face (face-centered).

  • Alloys - Materials that contain more than one element and have the characteristic properties of metals.

    • Substitutional alloys - A second element takes the place of a metal atom.

    • Interstitial alloys - A second element fills a space in the lattice of metal atoms.

    • Heterogeneous alloys - Components are not dispersed uniformly.

Metallic bonding

  • Electron sea model - Where we assume a metal is a group of cations suspended in a sea of electrons.

  • Molecular solids - Consist of atoms of molecules held together by weaker forces.

    • Shape - Ability to stack, it has influence on some physical properties like boiling point.

  • Covalent-network solids - Atoms are covalently bonded over large network distances with regular patterns of atoms.

    • They have higher melting and boiling points.

  • Coordination number - The number of nearest-neighbor atoms of an atom.

Polymers

  • Polymers - Molecules of high molecular weight made by joining smaller molecules called monomers.

    • They are mostly carbon-based.

    • They are formed by covalent bonding.

Primary polymers

  • Addition - Formed when a bond breaks and the electrons in that bond make two new bonds.

  • Condensation - Formed when a small molecule is removed between two larger molecules.

  • Copolymers - Formed by two different monomers.

Semiconductors on nanometers

  • Quantum dots - Semiconductor particles that are about 1-10nm.

  • Bond energy - Gap between highest occupied level and lowest unoccupied level.

  • Buckminsterfullerene or Buckyballs - Soccer ball-shaped C60 molecule.

HC

Chapter 12 - Solids and Modern Materials

Classifying solids based on bonds

  • Metallic solids - Held together by a sea of collectively shared electrons.

  • Ionic solids - Sets of cations and anions mutually attracted to one another.

  • Covalent-network solids - Joined by an extensive network of covalent bonds.

  • Molecular solids - Discrete molecules held together by weak forces.

Types of solids

  • Polymers - Contain a long chain of atoms connected by covalent bonds. They have different properties than small molecules or metallic ionic compounds.

  • Nanomaterials - Crystalline compounds with the crystals on the order of 1-100nm. They have different properties than larger crystalline materials.

  • Crystalline - Solids with a repeating pattern of atoms.

  • Amorphous - Lack of order in the arranged atoms.

Unit Cell

  • Unit cell - The basis of a repeating pattern.

  • The structure of a crystalline solid is defined by

    • Size and shape of unit cell

    • Location of atoms in the unit cell

  • Crystal lattice - Geometric pattern on which the unit cell is.

  • Lattice points - Positions that define the overall structure of the crystalline compound.

    • Each point has an identical environment.

Basic 3D lattices

  • Cubic

  • Tetragonal

  • Orthorhombic

  • Rhombohedral

  • Hexagonal

  • Monoclinic

  • Triclinic


  • Centered lattices - Have atoms in another regular location, most common in the body center (body-centered) or center of the face (face-centered).

  • Alloys - Materials that contain more than one element and have the characteristic properties of metals.

    • Substitutional alloys - A second element takes the place of a metal atom.

    • Interstitial alloys - A second element fills a space in the lattice of metal atoms.

    • Heterogeneous alloys - Components are not dispersed uniformly.

Metallic bonding

  • Electron sea model - Where we assume a metal is a group of cations suspended in a sea of electrons.

  • Molecular solids - Consist of atoms of molecules held together by weaker forces.

    • Shape - Ability to stack, it has influence on some physical properties like boiling point.

  • Covalent-network solids - Atoms are covalently bonded over large network distances with regular patterns of atoms.

    • They have higher melting and boiling points.

  • Coordination number - The number of nearest-neighbor atoms of an atom.

Polymers

  • Polymers - Molecules of high molecular weight made by joining smaller molecules called monomers.

    • They are mostly carbon-based.

    • They are formed by covalent bonding.

Primary polymers

  • Addition - Formed when a bond breaks and the electrons in that bond make two new bonds.

  • Condensation - Formed when a small molecule is removed between two larger molecules.

  • Copolymers - Formed by two different monomers.

Semiconductors on nanometers

  • Quantum dots - Semiconductor particles that are about 1-10nm.

  • Bond energy - Gap between highest occupied level and lowest unoccupied level.

  • Buckminsterfullerene or Buckyballs - Soccer ball-shaped C60 molecule.