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corresponds to its coefficient in the balanced chemical equation. At equilibrium
the mass action expression is equal to K; at other times it is Q.[C]c[D]d [A]a[B]b
= Q, or at equilibrium K
Mass Deficiency
The amount of matter that would be converted into energy if an atom were formed
from constituent particles.
Mass Number
The sum of the numbers of protons and neutrons in an atom; an integer.
Mass Spectrometer
An instrument that measures the charge-to-mass ratio of charged particles.
For further information see Mass Spectrometry
Matter
Anything that has mass and occupies space.
Mechanism
The sequence of steps by which reactants are converted into products.
Melting Point
The temperature at which liquid and solid coexist in equilibrium; also the freezing
point.
Meniscus
The shape assumed by the surface of a liquid in a cylindrical container.
Metal
An element below and to the left of the stepwise division (metalloids) in the upper
right corner of the periodic table; about 80% of the known elements are metals.
Metallic Bonding
Bonding within metals due to the electrical attraction of positively charges metal
ions for mobile electrons that belong to the crystal as a whole.
Metallic Conduction
Conduction of electrical current through a metal or along a metallic surface.
Metalloids
Elements with properties intermediate between metals and nonmetals: B, Al, Si,
Ge, As, Sb, Te, Po, and At.
Metallurgy
Refers to the overall processes by which metals are extracted from ores.
Metathesis Reactions
Reactions in which two compounds react to form two new compounds, with no
changes in oxidation number. Reactions in which the ions of two compounds
exchange partners.
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.
Miscibility
The ability of one liquid to mix with (dissolve in) another liquid.
Mixture
A sample of matter composed of two or more substances, each of which retains its
identity and properties.
Moderator
A substance such as hydrogen, deuterium, oxygen or paraffin capable of slowing
fast nuetrons upon collision.
Molality
Concentration expressed as number of moles of solute per kilogram of solvent.
Molarity
Number of moles of solute per litre of solution.
Molar Solubility
Number of moles of a solute that dissolve to produce a litre of saturated solution.
Molecular Equation
Equation for a chemical reaction in which all formulas are written as if all
substances existed as molecules; only complete formulas are used.
Molecular Formula
Formula that indicates the actual number of atoms present in a molecule of a
molecular substance.
Molecular Geometry
The arrangement of atoms (not lone pairs of electrons) around a central atom of a
molecule or polyatomic ion.
Molecular Orbital
An orbit resulting from overlap and mixing of atomic orbitals on different atoms.
An MO belongs to the molecule as a whole.
Molecular Orbital Theory
A theory of chemical bonding based upon the postulated existence of molecular
orbitals.
Molecular Weight
The mass of one molecule of a nonionic substance in atomic mass units.
Molecule
The smallest particle of an element or compound capable of a stable, independent
existence.
Mole Fraction
The number of moles of a component of a mixture divided by the total number of
moles in the mixture.
Monoprotic Acid
Acid that can form only one hydronium ion per molecule; may be strong or weak.
Acid that contains one ionizable hydrogen atom per formula unit.
Mother Nuclide
Nuclide that undergoes nuclear decay.
Native State
Refers to the occurrence of an element in an uncombined or free state in nature.
Natural Radioactivity
Spontaneous decomposition of an atom.
Nernst Equation
Corrects standard electrode potentials for nonstandard conditions.
Net Ionic Equation
Equation that results from canceling spectator ions and eliminating brackets from
a total ionic equation.
Neutralization
The reaction of an acid with a base to form a salt and water. Usually, the reaction
of hydrogen ions with hydrogen ions to form water molecules.
Neutron
A neutral subatomic particle having a mass of 1.0087 amu.
Nickel-cadmium cell (Nicad battery)
A dry cell in which the anode is Cd, the cathode is NiO2, and the electrolyte is
basic.
Nitrogenases
A class of enzymes found in bacteria within root nodules in some plants, which
catalyze reactions by which N2 molecules from the air are converted to ammonia.
For more information see Enzymes
Nitrogen Cycle
The complex series of reactions by which nitrogen is slowly but continually
recycled in the atmosphere, lithosphere and hydrosphere.
Noble Gases (Rare Gases)
Elements of the periodic Group 0; also called rare gases; formerly called inert
gases, He,Ne,Ar, Kr, Xe, Rn.
Nodal Plane
A region in which the probability of finding an electron is zero.
Nonbonding Orbital
A molecular orbital derived only from an atomic orbital of one atom; lends
neither stability nor instability to a molecule or ion when populated with
electrons.
Nonelectrolyte [ Pobierz całość w formacie PDF ]