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{ Glossary for Chemistry and Physics terms : 化学・物理の用語 説明 }
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A glossary for common Chemistry and Physics terms.
Absolute Temperature :
A scale for measuring temperature that is obtained by adding algebraically 273
to degrees centigrade.
Absolute Zero :
The temperature,273 degrees below the zero of the centigrade scale,at which all
molecular motion ceases.
Acid :
A compound which yields hydrogen ions in aqueous solution;a proton donor.
Addition reaction :
A reaction in which a reagent adds to a carbon-carbon double or triple bond.
Adsorption :
A process in which molecules or ions adhere to the surface of a solid.
Alkali :
A water soluble base that yields hydroxyl ions in aqueous solution.
Allotropism :
The property of certain elements of existing in more than one form,such as
oxygen and ozone.
Alpha particle :
The positively charged nucleus of the helium atom.
Anhydrous :
Without water.
Anion :
A negatively charged ion.
Anode :
The positively charged electrode of an electrolytic cell.
Atom :
The smallest unit of an element that participates in chemical change.
Atomic number :
A number,characteristic of an atom,that represents the number of protons in the
nucleus of the atom.It indicates the location of an element in the periodic
table.
Atomic weight :
The relative weight of an atom referred to carbon,whose weight has been
arbitrarily set at 12.01115.
Avogadro's law :
The law which states that equal volumes of all gases,at the same temperature
and pressure,contain the same number of molecules.
Base :
A compound which yields hydroxide ions in aqueous solution;a proton acceptor.
Beta particle :
A negative electron given off by a radioactive substance.
Binary compound :
A compound composed of two elements per molecule.
Boiling point :
The temperature at which the vapor pressure in a liquid equals the atmospheric
pressure.
Brownian movement :
The rapid oscillatory movement of small particles when suspended in water or
other liquids.
BTU :
British Thermal Unit,the quantity of heat required to raise the temperature of
one pound of water one degree Fahrenheit.It is equal to 0.252 calorie.
Buffer :
A substance that keeps the pH of a solution relatively constant in spite of the
addition of considerable amounts of acid or base.
Calorie :
A small calorie(cal.) is the amount of heat required to raise the temperature
of 1 gram of water by one degree Celsius.A large calorie(Cal.)equals 1000
calories.
Carboxyl group :
A univalent organic radical (-COOH) which is the functional group of all the
carbolic acids.
Catalyst :
A substance which speeds up,or less frequently retards,a chemical reaction,
without being changed itself.
Cathode :
The negatively charged electrode of an electrolytic cell.
Cation :
A positively charged ion.
Chemical change :
A change in which the chemical structure of a substance is changed.
Chemistry :
The science which deals with the composition and properties of substances and
their transformation from one form to another.
Colloids :
Particles which are intermediate in size between crystalloids that form true
solutions and suspensions that eventually settle.
Combining weight :
The weight of an element which will combine with 8 grams of oxygen,or 1.008
grams of hydrogen.
Combustion :
Rapid oxidation accompanied by evolution of heat and usually light.
Compound :
A substance composed of two or more elements united chemically in definite
proportions by weight.
Covalence :
The combining of atoms by means of the sharing of electrons.
Crystalloids :
Substances which,when dissolved in liquid,will diffuse through a semipermeable
membrane.
Dehydration :
The removal of water from a substance.
Deliquescence :
The process whereby certain substances absorb sufficient water from the atmos-
phere to dissolve themselves.
Denaturation :
The process of altering the structure of a protein by physical or chemical
means.
Density :
Mass per unit volume.
Deoxygenation :
The process of removing water from a compound.
Deuterium :
An isotope of hydrogen having twice the mass of ordinary hydrogen.
Diffusion :
The process by which one substance distributes itself uniformly through water.
Dispersion :
Colloidal particles suspended in a liquid medium.
Distillation :
The evaporation of a liquid and the condensation of it's vapor.
Efflorescence :
The spontaneous loss of water by a substance when exposed to air.
Electrolysis :
The decomposition of a chemical compound by an electrical current.
Electrolyte :
A substance which will conduct an electrical current when in solution or melted
Electron :
An atomic particle carrying a unit charge of negative electricity,having a mass
of 1/1837 of that of a proton.
Electrophoresis :
The migration of colloidal particles dispersed in a fluid,under the influence
of an electric field.
Electrovalence :
The valence as determined by the electrons lost or gained by the elements
reacting to form a compound.
Element :
One of the basic fundamental forms of matter that cannot be separated into
simpler substances by ordinary chemical means.
Emulsion :
A colloidal dispersion of a liquid in another liquid.
Endothermic reaction :
A chemical change in which heat is absorbed.
Energy :
The ability to do work.
Equilibrium :
A state existing in a reversable reaction when the rates of the forward and
reverse reactions are equal and the concentrations of the reactants and
products are equal.
Ester :
An organic compound formed by the reaction between an acid and an alcohol.
Exothermic reaction :
A chemical change in which heat is liberated.
Filtration :
The process of separating suspended particles from a liquid by means of a
porous medium.
Fission :
The disintegration of the nucleus of a heavy atom with the liberation of large
amounts of energy.
Formula :
An expression of the constituents of a compound by symbols.
Gamma ray :
Similar to X-rays,forming part of the radiation of a radioactive substance.
Gel :
A semi-rigid colloid.
Gram-atomic weight :
One atomic weight of an element expressed in grams.
Gram-molecular weight :
One molecular weight of a compound expressed in grams.
Half-life :
The length of time required for one-half of a radioactive substance to disinte-
grate.
Halide :
A compound composed of two elements,one of which is a halogen.
Halogens :
A family of elements consisting of flourine,chlorine,bromine and iodine.
Heterocyclic compounds :
Cyclic compounds in which the ring system of the molecule contains other
elements than carbon.
Hydrate :
A compound containing water of crystallization.
Hydride :
A compound containing a negatively charged hydrogen,as in sodium hydride(Na-H).
Hydrocarbons :
Organic compounds containing hydrogen and carbon only.
Hydrogenation :
A chemical reaction in which hydrogen is added to a compound.
Hydrolysis :
Chemical decomposition by which a compound is resolved into other compounds by
taking up the elements of hydrogen.
Hypertonic solution :
A solution of higher osmotic pressure than another with which it is compared.
Immiscible:
Incapable of being mixed,as oil and water.
Indicator :
A compound which changes color with changes in the hydrogen ion concentration
(pH)of a solution.
Iodine number :
The number of grams of iodine required to saturate 100 grams of fat.
Ion :
An electrically charged atom or radical.
Ionization :
The separation of an electrolyte into charged ions in solution.
Isoelectric point :
The pH at which a substance is electrically neutral or at it's minimum ioniza-
ation.
Isomers :
Compounds which have the same molecular formula but different structural
formulas.
Isotonic solution :
A solution having the same osmotic pressure as another with which it is
compared.
Isotopes :
Atoms of the same element having the same atomic number but having different
atomic weights.
Ketone :
An organic compound containing the carbonyl group attached to two organic
radicals.
Kindling temperature :
The lowest temperature at which a substance bursts into flame.
Kinetic energy :
Energy in motion.
Latent heat :
The heat absorbed in the changing of a substance from solid to liquid,or from a
liquid to a gas.
Matter :
Anything which occupies space and has mass.
Miscible :
Capable of being mixed.
Mixture :
An aggregate of two or more substances which are not chemically combined and
which exist in no fixed proportion to one another.
Molal solution :
A solution containing one mole of a solute in 1,000 grams of solute.
Molar solution :
A solution which contains 1 gram-molecular weight of solute in one liter of
solution.
Mole :
The molecular weight of a substance expressed in grams.
Molecular weight :
The sum of the atomic weights of all the atoms in a molecule.
Molecule :
The smallest particle of a compound that can exist independently.
Nascent :
The condition of an element that has just been released in the monatomic state
in a chemical reaction.
Neutron :
A neutral particle existing in the nucleus of an atom.
Noble gases :
A family of elements consisting of helium,neon,argon,krypton,xenon and radon.
Nonelectrolyte :
A compound whose water solution does not conduct an electric current.
Normal solution :
A solution which contains 1 gram-equivalent weight of a solute in 21 liters of
solution.
Nucleic acid :
An organic compound composed of phosphoric acid,ribose or deoxyribose,and
purine and pyride bases.
Nucleus :
The positively charged center of the atom containing protons and neutrons.
Osmosis :
The passage of fluid from a less concentrated solution to a more concentrated
solution through a semipermeable membrane.
Oxidation :
Combination of a substance with oxygen;the increase in valence toward the
positive;the loss of electrons.
Oxide :
A compound of oxygen and some other element.
Periodic law :
The law that the properties of the elements are periodic functions of their
atomic numbers.
Periodic table :
A table illustrating the periodic system in which the chemical elements
arranged in the order of their atomic numbers are shown in related groups.
pH :
A symbol denoting the algorithm of the reciprocal of hydrogen ion concentration
Physical change :
A change in the condition or state of a substance;it's composition is not
altered.
Potential energy :
Energy that is due to position and not of motion;stored energy.
Precipitate :
An insoluble liquid that separates from solution.
Protein :
A substance of high molecular weight composed of carbon,hydrogen,nitrogen,and
sometimes sulphur or iodine,that yields upon hydrolysis amino acids or their
derivatives.
Proton :
A subatomic particle carrying a unit of positive charge.
Radical :
A group of atoms that behave as a unit in a chemical reaction.
Radioactivity :
The spontaneous disintegration of an atom,with the emission of alpha.beta,and
gamma rays.
Radioisotope :
A radioactive isotope,often used as a tracer in scientific research.
Reduction :
The removal of oxygen from a compound;the gain of electrons by a substance or a
decrease in it's valence.
Salt :
A compound consisting of a positive ion other than hydrogen and a negative ion
other than the hydroxyle ion;the product of an acid with a base.
Saturated solution :
A solution that contains all the solute that it can hold at a given temperature
and pressure.
Semipermeable membrane :
A membrane that allows water and crystalloids to pass through but holds back
colloids.
Solute :
A substance dissolved in a solvent.
Solution :
A homogeneous mixture of two or more substances.
Solvent :
A substance in which a solute is dissolved.
Specific gravity :
The ratio of the weight of a given volume of a substance to the weight of an
equal volume of water.
Specific heat :
The quantity of heat in calories required to raise the temperature of one gram
of a substance one degree Celsius.
Spontaneous combustion :
The ignition of a substance as the result of the accumulated heat of slow
oxidation.
Structural formula :
A formula which shows the arrangement of the atoms in a molecule.
Substitution reaction :
A chemical reaction in which one or more elements or radicals in a compound are
replaced by other elements or radicals.
Suspension :
A system consisting of small particles dispersed in a liquid.The particles will
settle out slowly upon standing.
Synersis :
The shrinking of a gel,with the expulsion of water or other liquid from it.
Synthesis :
The construction of a compound by the union of elements or simple compounds.
Tincture :
A solution of a medicinal substance in alcohol.
Titration :
The process of determining the quantity of a substance in a solution by adding
a measured volume of a standard solution until the desired reaction has been
affected.
Transmutation :
The conversion of one element into another in a nuclear reaction.
Tyndall effect :
The reflection of a beam of light by the dispersed particles of a colloidal
solution,making visible the path of the light.
Unsaturated compounds :
Organic compounds containing double or triple bonds and are capable of forming
addition products.
Unsaturated solution :
A solution containing less solute than the amount needed to make a saturated
solution.
Valence :
A number that represents the combining power of an element or radical.
Valence electrons :
The electrons located in the outermost shell of an atom.
Water of crystallization :
Water present in the crystal of a hydrate.
Zwitterion :
A dipolar ion carrying both a positive and a negative charge.
__[ Source ]__
THE CHEMISTRY REFERENCE LIBRARY VERSION 1.00
(C)COPYRIGHT DAVID KRAMER 1987; CHEMPROG.ZIP
File : 3.DTA
