54 terms

EEE-3394 Chapter 1 Terms


Terms in this set (...)

Activated State
the temporary state during a transformation or reaction when the combination of reactants and products have a higher PE than the reactants.
Activation Energy
PE barrier against the formation of a product; the minimum energy that the reactant must have to reach activated state.
Amorphous Solid
a solid that exhibits no crystalline structure or long-range order.
an atom that has gained negative charge by accepting one or more electrons.
Atomic Mass
average atomic mass of all naturally occurring isotopes of the element.
an identical group of atoms, or molecules, placed at each lattice point, creating a crystal structure.
Bond Energy
the work needed to separate two atoms infinitely from their equilibrium separation in the molecule or solid.
an atom that has gained a positive charge by losing one or more electrons.
Coordination Number
the number of nearest neighbors around a given atom in the crystal.
Covalent Bond
the sharing of a pair of valence electrons between two atoms.
a 3D periodic arrangement of atoms, molecules, or ions. Has long-range order with a well-defined bond length and relative bond angle (having periodicity and a degree of symmetry).
a process by which crystals of a substance are formed from another phase of that substance.
the migration of atoms by virtue of their random thermal motions.
Diffusion Coefficient
the rate at which atoms diffuse.
a line imperfection with a crystal that extends over many atomic distances.
Edge Dislocation
a line defect formed in a crystal when an atomic plane within the crystal does not extend all the way through. Has compression above the line and expansion below it.
Electric Dipole Moment
two separated charges with equal magnitude but opposite signs.
Electron Affinity
energy needed to attract an electron
how well an atom can attract electrons in a bond it forms with another atom.
two systems having mechanical, thermal, and chemical equilibrium.
Equilibrium State
when pressure and temperature in the system are uniform throughout (possessing mechanical and thermal equilibrium).
Eutectic Composition
an alloy composition of two elements that results in the lowest melting temperature compared to any other composition.
Face-Centered Cubic (FCC) Lattice
a cubic lattice that has one lattice point at each corner of a cube and one at the center of each face.
Frenkel Defect
an ionic crystal imperfection that occurs when an ion moves into an interstitial site, thereby creating a vacancy in its original site; a pair of point defects.
an individual crystal within a polycrystalline material.
Grain Boundary
a high-energy region where grains of different orientation meet. Lots of defects, voids, and broken bonds occur here. Diffusion happens more easily here as well.
Interstitial Site (Interstice)
an unoccupied space between the atoms in a crystal.
Ionization Energy
the energy required to remove an electron from a neutral atom.
describes a structure that is the same everywhere.
Isotropic Substance
a material that has the same property in all directions.
Kinetic Molecular Theory
atom and molecules of all substance above absolute zero of temperature are in constant motion
an infinite periodic array of geometric points in space, w/o any atoms. There are 14 distinct lattices possible in 3D space.
Lattice Parameters
are the lengths of the sides of the unit cell and the angles between the sides.
Mechanical Work
the energy expended in displacing a constant force through a distance.
Metallic Bonding
the binding of metal atoms in a crystal through the attraction between the positive metal ions and the mobile valence electrons in the crystal.
Miller Indices
are indices that conveniently identify parallel planes in a crystal.
how soluble two substance are while in the same phase.
has the same composition, structure, and properties everywhere.
Phase Diagram
a temperature versus composition diagram in which various phases are identified by regions and lines.
Planar Concentration of Atoms
the number of atoms per unit area on a given plane in a crystal.
the separation of charges w/opposite signs in a system, resulting in an electric dipole moment.
Polymorphism or Allotropy
a material possessing more than one crystal structure.
Primary Bond
a strong interatomic bond that involves ionic, covalent, or metallic bonding.
Saturated Solution
a solution that has the maximum possible amount of solute dissolved in a given amount of solvent.
Schottky Defect
an ionic crystal imperfection that occurs when a pair of ions is missing; when there is a cation and anion pair vacancy.
Screw Dislocation
twisting or skewing of one portion of a crystal WRT another portion.
Secondary Bond
a weak bond which is due to dipole-dipole interactions between the atoms or molecules.
Solid Solution
a homogeneous mixture of two or more types of separate atoms.
the minor chemical component of a solution.
the major chemical component of a solution.
Stoichiometric Compounds
compounds with an integer ratio of atoms.
Unit Cell
the most convenient small cell in a crystal structure that carries the characteristics of the crystal.
a point defect in a crystal, where a normally occupied lattice site is missing an atom.
Valence Electrons
the electrons in the outer shell of an atom.