Ch 10 Section 3 Flashcards
the particles of a solid are more closely packed than those of a
liquid or gas
intermolecular forces between particles are therefore much more
effective in solids
all interparticle attractions exert stronger effects in solids than in the corresponding
liquids or gases
attractive forces tend to hold the particles of a solid in
relatively fixed points, with only vibrational movement around fixed points
because the motions of the particles are restricted in this way, solids are more ordered than
liquids and are much more ordered than gases
there are two types of solids:
crystalline solids and amorphous solids
Most solids are crystalline solids→they
consist of crystals
a crystal is a substance in which the particles are arranged in an
orderly, geometric, repeating pattern
noncrystalline solids, including glass and particles, are called
amorphous solids
an amorphous solid is one in which the particles are arranged
randomly
unlike liquids and gases, solids can maintain a definite
shape without a container
crystalline solids are
geometrically regular
even the fragments of a shattered crystalline solid have distinct
geometric shapes that reflect their internal structure
amorphous solids maintain a definite shape, but they do not have the
distinct geometric shapes of crystalline solids
the volume of a solid changes only slightly with a change in
temperature or pressure
solids have definite volume because their particles are
packed closely together
there is very little empty space into which the particles can be
compressed
crystalline solids generally do not flow because their particles are held in
relatively fixed positions
melting is the physical change of a solid to a liquid by the addition of
energy as heat
the temperature at which a solid becomes a liquid is its
melting point
at this temperature, the kinetic energies of the particles within the solid overcome the a
attractive forces holding them together
the particles can then break out of their positions in
crystalline solids, which have definite melting points
amorphous solids have no definite
melting point
amorphous solids have the ability to flow over a
range of temperatures
amorphous solids are sometimes classified as supercooled liquids, which are substances that retain certain liquid properties even at
temperatures at which they appear to be solid
these properties exist because the particles in amorphous solids are arranged
randomly, much like the particles in a liquid
unlike the particles in a true liquid, however, the particles in amorphous solids are not
constantly changing their positions
substances are most dense in the
solid state
solids tend to be slightly denser than
liquids and much denser than gases
the higher density results from the fact that the particles of a solid are more
closely packed than those of a liquid or a gas
solid hydrogen is the least dense solid; it has a density of about
1/320 the densest element, osmium
solids are generally less compressible than
liquids
some solids, such as wood and cork, may seem compressible, but they are
not
diffusion does occur in
solids
the rate of diffusion in solids is millions of times slower than in
liquids
crystalline solids exist either as single crystals or as
groups of crystals fused together
the total 3d arrangement of particles of a crystal is called a
crystal structure
the arrangement of particles in the crystal can be represented by a coordinate system called a
lattice
the smallest portion of a crystal lattice that shows the three-dimensional pattern of the entire lattice is called a
unit cell
each crystal lattice contains many
unit cells packed together
a crystal and its unit cells can have any one of
seven types of symmetry which enables scientists to classify crystals by their shape
crystal structures can also be described in terms of the types of particles in them and the types of
chemical bonding between the particles
(types of crystals) ionic crystals: ionic crystal structure consists of positive and
negative ions arranged in a regular pattern
(types of crystals) ionic crystals: the ions can be monatomic or
polyatomic
(types of crystals) ionic crystals: ionic crystals form when group 1 or group 2 metals combine with group 16 or group 17
nonmetals or nonmetallic polyatomic ions
(types of crystals) ionic crystals: the strong binding forces between the positive and negative ions in the crystal structure give the ionic crystals
certain properties→hardness, brittleness, high melting pts., good insulators
(types of crystals) covalent network crystals: each atom is covalently bonded to its
nearest neighboring atoms
(types of crystals) covalent network crystals: the covalent bonding extends throughout a network that includes a
very large number of atoms
(types of crystals) covalent network crystals: three-dimensional covalent network solids include
diamond, quartz, silicon carbide, and many oxides of transition metals
(types of crystals) covalent network crystals: the subscript x in these formulas (e.g. (SiO2)x ) indicates that the component within the parentheses
extends indefinitely
(types of crystals) covalent network crystals: the network solids are nearly always very
hard and brittle
(types of crystals) covalent network crystals: they have rather high melting points and are usually
nonconductors or semiconductors
(types of crystals) metallic crystals: the metallic crystal structure consists of
metal cations surrounded by a sea of delocalized valence electrons
(types of crystals) metallic crystals: the electrons come from the metal atoms and belong to the
crystal as a whole
(types of crystals) metallic crystals: the freedom of these delocalized electrons to move throughout the crystal explains the
high electric conductivity of metals
(types of crystals) covalent molecular crystals: the crystal structure of a covalent molecular substance consists of covalently bonded
molecules held together by intermolecular forces
(types of crystals) covalent molecular crystals: if the molecules are nonpolar then there are only weak
London dispersion forces between molecules (e.g. hydrogen, methane, benzene C6H6)
(types of crystals) covalent molecular crystals: in a polar covalent molecular crystal molecules are
held together by dispersion forces, somewhat stronger dipole-dipole forces, and sometimes by even stronger hydrogen bonding (e.g. H20, ammonia NH3)
(types of crystals) covalent molecular crystals: the forces that hold polar/nonpolar molecules together in the structure are much weaker than the
covalent chemical bonds between the atoms within each molecule
(types of crystals) covalent molecular crystals: covalent molecular crystals thus have
low melting points
(types of crystals) covalent molecular crystals: easily…, are relatively…, and are good…
vaporized; soft; insulators
amorphous comes from greek word for
without shape
the atoms that make up amorphous solids are not arranged in
a regular pattern
glasses are made by cooling certain molten materials in a way that
prevents them from crystallizing
plastics (amorphous solid) are easily molded at high
temperatures and pressures and are used in many structural materials
amorphous semiconductors are used in
electronic devices
