Solids
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Solids. Two major types: Amorphous- those with much disorder in their structure. Crystalline- have a regular arrangement of components in their structure. Crystalline Solids. Lattice- a three dimensional grid that describes the locations of the pieces in a crystalline solid.

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Solids
Solids

  • Two major types:

    • Amorphous- those with much disorder in their structure.

    • Crystalline- have a regular arrangement of components in their structure.


Crystalline solids
Crystalline Solids

  • Lattice- a three dimensional grid that describes the locations of the pieces in a crystalline solid.

  • Unit Cell-The smallest repeating unit of the lattice.


Simple cubic
Simple Cubic

Number of atoms per unit cell?

1


Body centered cubic
Body-Centered Cubic

Number of atoms per unit cell?

2


Face centered cubic
Face-Centered Cubic

Number of atoms per unit cell?

4


Body-centered Cubic

Face-centered Cubic

Simple Cubic


Types of crystalline solids
Types of Crystalline Solids

  • Ionic solids have ions at the lattice points.

  • Molecular solids have molecules.

    • Polar

    • Nonpolar

  • Atomic Solids:

    • Metallic crystals have positive metal ions.

    • Group 8A crystals have atoms.

    • Network solids have covalently-bound atoms.


Ionic solids
Ionic Solids

  • Particles are held together by attraction of opposite charges.

  • Huge melting and boiling points.

  • Particles are locked in lattice positions, so sample is hard and brittle.

  • Every electron is accounted for so they are poor conductors-good insulators.


Molecular solids
Molecular solids

  • Molecules occupy the corners of the lattices.

  • Different types of molecules have different intermolecular forces.


Nonpolar molecular solids
Nonpolar Molecular Solids

  • The only forces are _______________ _______________________________

    • Strength depends on ________________ _________________________________

  • Most are gases at 25ºC.


Polar molecular solids
Polar Molecular Solids

  • Possible IMFs: _____________________ _________________________________

  • Dipole-dipole forces are generally stronger than dispersion forces.

  • Hydrogen bonding is stronger than Dipole-dipole forces.

  • No matter how strong the intermolecular force, it is always much, much weaker than the forces in bonds.


Metallic solids
Metallic Solids

  • Electron sea model – array of metal cations in a “sea” of mobile valence electrons


Metallic solids1
Metallic Solids

  • Electron sea model accounts for known properties of metals:

    • Malleable

    • Ductile

    • Good conductors of heat and electricity

    • High melting points

  • Internal bonding must be both strong and nondirectional


Atomic solids nonmetallic
Atomic Solids (Nonmetallic)

  • The only forces are _______________ _______________________________

    • Strength depends on ________________ _________________________________


Network covalent solids
Network Covalent Solids

  • Atoms at points of lattice.

  • Atoms held together in 3-d network by covalent bonds.

  • VERY few examples. Memorizethese:

    C(diamond), SiO2(quartz), SiC


Silicon dioxide
Silicon Dioxide

  • also called silica

  • quartz, sand


Carbon is special
Carbon Is Special

allotropes

There are many types of solid carbon:

  • Coal – amorphous

  • Diamond- hardest natural substance on earth, insulates both heat and electricity

  • Graphite- slippery, conducts electricity

  • Fullerenes – strong, good conductors of heat and electricity


Diamond

  • each Carbon is sp3 hybridized, connected to four other carbons.

  • Strong array of s bonds

    • top on the Mohs hardness scale

    • very high melting point

    • nonconducting



Graphite is different
Graphite is different.

  • Each carbon is connected to three other carbons and sp2 hybridized.

  • Flat sheets of 6 member rings with 120º angles throughout

  • The p bonds extend above and below each sheet.


Graphite is different1
Graphite is different.

  • p orbitals overlap forming a huge p bonding network.

  • Electrons are free to move through out these delocalized orbitals.

    • The layers slide by each other.


Fullerenes

  • composed entirely of carbon

  • spherical, elliptical, or hollow tube

C60

Buckminster fullerene

Carbon nanotubes


Types of Crystals

Types of

Interparticle Attractions


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