50 terms

Chemistry Ch.11 part 2

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Crystalline solid
has atoms, ions, or molecules arranged in a well ordered structure.
Amorphous
does not have a well ordered structure.
Crystalline solid
have a distinct three dimensional structure with a sharp melting point
amorphous solid
do not have a distinct three dimensional structure and do not have a sharp melting point. They slowly soften over a broad temperature range.
Unit cell
smallest pattern of a crystal structure that repeats in a ll directions
simple cubic, tetragonal, orthorhombic, rhombohedral, monoclinic, triclinic, and hexagonal
Seven types of unit cells
a=b=c; a=B=y=90
Describe a simple cubic unit cell structure
a=b/c; a=y=90, B=120
Describe a Hexagonal unit cell structure
Lattice points
positions in the unit cell that are occupied by atoms, ions, or molecules
simple cubic, body-centered (bcc), and face-centered cubic (fcc)
Three basic types of cubic unit cells
Simple cubic
a cube with atoms (molecules or ions) only at the eight corners
Body-centered cubic
a cube with atoms (molecules) at the eight corners plus one more in the center of the cube
Face-centered cubic
a cube with atoms (molecules) at the eight corners plus six more in the center of each of the six faces of the cube
8(1/8)=1
How many particles per unit cell for Simple cubic?
8(1/8)+1(1)=2
How many particles per unit cell for Body-centered cubic?
8(1/8)+6(1/2)=4
How many particles per unit cell for Face-centered cubic?
coordination number
the number of ions of opposite charge that surround the ion in a crystal
12
What is the coordination number of Face-centered cubic?
6
What is the coordination number of primitive cubic?
8
What is the coordination number of Body-centered cubic?
a-a-a-a-
Stacking pattern of a simple cubic structure.
a-b-a-b-
Stacking pattern of a Body-centered cubic structure.
a-b-a-b-
Stacking pattern of a Hexagonal closeted packed structure.
a-b-c-a-b-c-
Stacking pattern of a cubic closest-packed cubic structure.
68%
Spaced used in a Body-centered cubic structure
52%
Spaced used in a simple cubic structure.
74%
Spaced used in a Hexagonal closest-packed structure.
74%
Spaced used in a cubic closest-packed structure.
Primitive-cubic unit cell
Unit cells used in a simple cubic structure
Body-centered cubic unit cell
Unit cells used in a Bod-centered cubic strucutre
Noncubic unit cell
Unit cells used in a hexagonal closest-packed structure
Face-centered cubic unit cell
Unit cells used in a cubic closest-packed structure
Ionic, molecular, covalent-network, and metallic
Types of crystalline solids
Ionic Solids
Consist of ions (cations and
anions) held together by ionic bonding (strong
electrostatic attraction).
Ionic solid properties
Relatively hard
High melting points
Brittle
Do not conduct electricity as solids (molten
state conducts electricity)
Molecular Solids
Consist of atoms or molecules
held together by intermolecular forces.
Molecular solids
Typically soft with low melting points due to
weak attractive forces.
Covalent-Network solids
Consist of atoms held together by strong covalent bonds in a large network.
Covalent-Network solids
much harder with higher melting points
than molecular solids; stronger forces of
attraction between atoms.
Metallic Solids
Consist of metal atoms that
are packed together so that they are touching.
Diamond structure
Extended array of C atoms
bonded together with single covalent bonds.
Diamond structure
Very hard; very high melting point (3550 ºC).
These solids are the hardest
substances known
6
How many Na+ ions surround each Cl- ion in a NaCl structure(coordination number)?
NaBr, KCl, MgO, M^+M^-, and M^2+M^2-
Which other ions have the same unit cell structure as NaCl?
NaCl crystal structure
CsCl crystal structure
8
Coordination number of CsCl crystal structure
Graphite structure
consist of two dimensional array of carbon atoms
Hexagonal rings
slide past one another easily to give graphite structures a slippery feel
diamond and graphite (both C), SiO2, SiC, B, BN, and Si
Name the Network solids that you must have committed to memory
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