SOLIDS Flashcards
with considerable disorder in their
structures.
AMORPHOUS SOLID
Disordered, disorganized, random,
no lattice
AMORPHOUS SOLID
highly regular arrangement of their
components
CRYSTALLINE SOLIDS
Ordered, organized, regularly
repeating, has lattice structure
Ordered, organized, regularly
repeating, has lattice structure
_____ ___s keep the particles from
changing positions relative to each other
Strong IMFs
The regular arrangement of the
components of a crystalline solid at the
microscopic level produces the
beautiful, characteristic shapes of
crystals.
Unit Cells & Lattices
The positions of the components are
represented by a _______, a 3D system of
points designating the positions of the
components (atoms, ions, or molecules)
that make up the substance. repeatable crystal structure
lattice
smallest repeating unit
unit cell
Structures of Crystalline Solids are Determined by ____ ___________
X-ray diffraction
beams of light are
scattered from a regular array of points
X-ray diffraction
When X rays of a single wavelength are
directed at a crystal, a diffraction pattern
is obtained. The light and dark areas on
the photographic plate occur because the
waves scattered from various atoms may
_________ or ______ each other depending
on the ________ traveled by the waves
after they strike the atoms.
Reinforce, Cancel, Distance
The diffraction pattern can be used to
determine the interatomic spacings using
_____ equation.
Bragg Equation
A diffraction pattern of a beryl crystal. Light area
(_______ _______), dark area
(______ ________ __ _____)
Light area
(constructive interference), dark area
(destructive interference of waves)
TYPES OF CRYSTALLINE SOLIDS
MOLECULAR, IONIC & ATOMIC
has discrete covalently
bonded molecules at each
of its lattice points
MOLECULAR SOLIDS
have ions at the points of the
lattice that describes the
structure of the solid, Cations and anions held by ionic bonds.
IONIC SOLIDS
have atoms at the lattice
points that describe the
structure of the solid
ATOMIC SOLIDS
convenient to classify solids according to what type of component occupies
the lattice points
Classification of Solids
The internal forcesin a solid determine the properties of the solid.
Classification of Solids
Characterized
by high thermal and
electrical conductivity,
malleability, and ductility
Metals
Type of bonding that will occur depends on the elements involved
Chemical Bonding
metal + nonmetal = ?
metal + nonmetal = ionic bond
nonmetal/metalloid + nonmetal = ?
nonmetal/metalloid + nonmetal = covalent bond
metal + metal = ?
metal + metal = metallic bond
strength of metallic bonding depends on ______ __ __________
degree of attraction
strength of metallic bonding does not depend on ___________
directionality
The closest packing model (an
arrangement of structure in a
manner that most efficiently uses
the available space) for metallic
crystals assumes that metal atoms
are uniform, hard spheres.
Structure & Bonding in Metals
hexagonal closest packed (hcp)
structure = ___ arrangement
aba arrangement
cubic closest packed (ccp)
structure = ___ arrangement
abc arrangement
substance that contains a mixture of elements and
has metallic properties
Metal Alloys
some of the host metal atoms are replaced by
other metal atoms of similar size
substitutional alloy
interstitial alloy
formed when some of the interstices (holes) in the
closest packed metal structure are occupied by small atoms
Many atomic solids contain strong directional
covalent bonds to form a solid that might best
be viewed as a “giant molecule” (network
solids)
Network Atomic Solid: C & Si
typically brittle
and do not
efficiently
conduct heat
or electricity
Network Atomic Solid: C & Si
Different structural forms of the same element in the same physical state
Allotrope
4 Allotropes of C:
Diamond Graphite, Graphene & Fullerenes
network of SiO4
tetrahedra; O/Si ratio is 2:1
silica
salts containing metal cations &
polyatomic Si–O anions; O/Si ratios > 2:1
silicates
an amorphous solid formed when silica is heated above its
melting point (about 1600°C) and cooled rapidly
Glass
more closely resembles a very viscous solution than it does
a crystalline solid; can be melted & remelted as often as desired
(homogeneous, noncrystalline “frozen solution,”)
Glass
properties of these can be varied greatly by varying the additives
Glass
typically made from clays (which contain silicates) and
hardened by firing at high temperatures.
Ceramic
nonmetallic materials that are strong, brittle, and resistant to
heat and attack by chemicals
Ceramic
heterogenous (contains 2 phases: minute crystals of silicates
that are suspended in a glassy cement)
Ceramic
at higher temperatures, where more energy is
available to excite electrons into the conduction
bands, the conductivity of Si increases ( typical
behavior for a semiconducting element) and is in
contrast to that of metals, whose conductivity
decreases with increasing temperature.
Semiconductors
Elemental Si has the same structure as diamond
(large energy gap between the filled & empty
MO which prevents excitation of electrons,
hence insulators) but at 25°C, a few electrons
can cross the gap
making Si a semiconducting
element, or semiconductor.
The small conductivity of ______
can be enhanced at normal temp if
the Si crystal is doped with certain
other elements & become n-type or
p-type semiconductors
silicon
convenient way of representing the phases of a substance as a
function of temperature and pressure
Phase Diagrams
The enthalpy change that occurs at the MP
when a solid melts is called the
____/_________ __ ______
heat/enthalpy of fusion
The ______ _____ (not drawn to scale) for
water where E is added at a constant rate.
heating curve
