Module 3 Flashcards
materials that contain more than one element
alloys
types of alloys
SIH
SUBSTITUTIONAL, INTERSTITIAL, HETEROGENOUS ALLOYS
element takes place of a metal atom
substitutional alloys
element that fills a space in the lattice of metal atoms
interstitial alloys
components not dispersed uniformly
heterogeneous alloys
compounds not mixtures
distinct properties, definite composition, ordered rather than randomly distributed , more brittle than substitutional alloys
intermetallic compounds
a group of cations suspended in a sea of electrons
metallic bonding
the electron sea model would lead to increased attraction for every
electron added
Rules of MO theory
- atomic orbitals combine to make MOs to extend over the entire molecule
- MO can contain 0,1,2 electrons
- number of MOs equal the number of atomic orbitals
- adding electrons to a bonding MO strengthens bonding, while adding them to antibonding MOs weakens bonding
the number of atoms in a chain increases, the energy gap disappears resulting in
continuous band of energy
held together by electrostatic attractions
ionic solids
have very high melting and boiling points
ionic solids
the charge is centered on the anions they are called
electronic insulators
three common structures
CsCl structure
NaCl structure
Zinc blende
consist of atoms or molecules held together by weaker forces
molecular solids
ability to stack matters for some physical properties, like boiling point
shape
example of molecular solids
graphite
atoms are covalently bonded over large network distances with regular patterns of atoms
covalent-network solids
example of covalent network solids
diamond
have a gap between the occupied and not occupied band
semiconductors
tend to have an average of four valence electrons
iorganic semiconductors
have more electrons, so the negative charge travel in conductance band
n-type semiconductors
have fewer electrons, so the hole travels in the valence band
p-type semiconductors
are molecules of high molecular weight made by joining smaller molecules
polymers
polymers are molecules of high molecular weight made by joining smaller molecules
monomers
polymeric solids that can be formed into various shapes
plastics
TYPES OF PLASTICS
Thermoplastics, thermosetting plastics, and elastomers
a type of plastic that can be melted and reshaped
thermoplastics
type of plastics that can be shaped through an irreversible chemical reaction
thermosetting plastics
are rubbery, they stretch and return to shape
elastomers
TYPES OF POLYMERS
AC
Addition polymers
Condensation polymers
formed when a bond breaks and the electrons in that bond make two new bonds
addition polymers
are formed when a small molecule is removed between two large molecules
condensation polymers
two molecules are joined to make a larger molecule
condensation polymerization
formed by two different monomers
copolymers
can lead to crystallinity in the solid that makes the polymer denser, harder, less, and more resistant to heat
short range order
in vulcanization chains are cross-linked by short chains of
sulfur atoms
are semiconductors 1-10 nanometers in size
quantum dots
allotropes of carbon
diamond, graphite, graphene, and buckyballs
the only allotropes of carbon known were
diamond and graphite
a new form of carbon that exist is discovered
discrete C60 molecules
another name of buckyballs
buckminsterfullerene
a single layer with the structure of graphite
graphene
