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A rare metallic element found in gadolinite and forming compounds resembling those of yttrium. Symbol: Yb, at. wt.: 173.04, at. no.: 70, sp. gr.: 6.96. Cf."rare-earth element."

 

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Salinometer

An instrument for measuring the amount of salt in a solution. Also,"salimeter, salometer."

Born-Haber Cycle

A series of reactions (and accompanying enthalpy changes) which, when summed, represents the hypothetical one-step reaction by which elements in their standard states are converted into crystals of ionic compounds (and the accompanying enthalpy changes.)

Coordinate Covalent Bond

A covalent bond in which both shared electrons are donated by the same atom, a bond between a Lewis base and a Lewis acid.

Net Ionic Equation

Equation that results from canceling spectator ions and eliminating brackets from a total ionic equation.

Chain Termination Step

The combination of two radicals, which removes the reactive species that propagate the change reaction.

Electrolysis

Process that occurs in electrolytic cells.

Hydrophilic Colloids

Colloidal particles that repel water molecules.

Crystal Lattice

A pattern of arrangement of particles in a crystal.

Hess' Law of Heat Summation

The enthalpy change for a reaction is the same whether it occurs in one step or a series of steps.

Method of Initial Rates

Method of determining the rate-law expression by carrying out a reaction with different initial concentrations and analyzing the resultant changes in initial rates.

Nucleus

The very small, very dense, positively charged center of an atom containing protons and neutrons, as well as other subatomic particles.

Nonpolar Bond

Covalent bond in which electron density is symmetrically distributed.

Quantum Numbers

Numbers that describe the energies of electrons in atoms, derived from quantum mechanical treatment.

Effective Nuclear Charge

The nuclear charge experienced by the outermost electrons of an atom, the actual nuclear charge minus the effects of shielding due to inner-shell electrons.
Example: Set of dx2-y2 and dz2 orbitals, those d orbitals within a set with lobes directed along the x-, y-, and z-axes.

Solution

Homogeneous mixture of two or more substances.

Effective Collisons

Collision between molecules resulting in a reaction, one in which the molecules collide with proper relative orientations and sufficient energy to react.

 

Ideal Gas

A hypothetical gas that obeys exactly all postulates of the kinetic-molecular theory.

 

Barometer

A device for measuring pressure.

Liquid Aerosol

Colloidal suspension of liquid in gas.

Composition Stoichiometry

Descibes the quantitative (mass) relationships among elements in compounds.