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periodic law definitions

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WordNet (r) 3.0 (2005)

n
1: (chemistry) the principle that chemical properties of the elements are periodic functions of their atomic numbers [syn: periodic law, Mendeleev's law]

Merriam Webster's

noun Date: 1872 a law in chemistry: the elements when arranged in the order of their atomic numbers show a periodic variation of atomic structure and of most of their properties

Webster's 1913 Dictionary

Law of Charles (Physics), the law that the volume of a given mass of gas increases or decreases, by a definite fraction of its value for a given rise or fall of temperature; -- sometimes less correctly styled Gay Lussac's law, or Dalton's law. Law of nations. See International law, under International. Law of nature. (a) A broad generalization expressive of the constant action, or effect, of natural conditions; as, death is a law of nature; self-defense is a law of nature. See Law, 4. (b) A term denoting the standard, or system, of morality deducible from a study of the nature and natural relations of human beings independent of supernatural revelation or of municipal and social usages. Law of the land, due process of law; the general law of the land. Laws of honor. See under Honor. Laws of motion (Physics), three laws defined by Sir Isaac Newton: (1) Every body perseveres in its state of rest or of moving uniformly in a straight line, except so far as it is made to change that state by external force. (2) Change of motion is proportional to the impressed force, and takes place in the direction in which the force is impressed. (3) Reaction is always equal and opposite to action, that is to say, the actions of two bodies upon each other are always equal and in opposite directions. Marine law, or Maritime law, the law of the sea; a branch of the law merchant relating to the affairs of the sea, such as seamen, ships, shipping, navigation, and the like. --Bouvier. Mariotte's law. See Boyle's law (above). Martial law.See under Martial. Military law, a branch of the general municipal law, consisting of rules ordained for the government of the military force of a state in peace and war, and administered in courts martial. --Kent. Warren's Blackstone. Moral law,the law of duty as regards what is right and wrong in the sight of God; specifically, the ten commandments given by Moses. See Law, 2. Mosaic, or Ceremonial, law. (Script.) See Law, 3. Municipal, or Positive, law, a rule prescribed by the supreme power of a state, declaring some right, enforcing some duty, or prohibiting some act; -- distinguished from international and constitutional law. See Law, 1. Periodic law. (Chem.) See under Periodic. Roman law, the system of principles and laws found in the codes and treatises of the lawmakers and jurists of ancient Rome, and incorporated more or less into the laws of the several European countries and colonies founded by them. See Civil law (above). Statute law, the law as stated in statutes or positive enactments of the legislative body. Sumptuary law. See under Sumptuary. To go to law, to seek a settlement of any matter by bringing it before the courts of law; to sue or prosecute some one. To take, or have, the law of, to bring the law to bear upon; as, to take the law of one's neighbor. --Addison. Wager of law. See under Wager. Syn: Justice; equity. Usage: Law, Statute, Common law, Regulation, Edict, Decree. Law is generic, and, when used with reference to, or in connection with, the other words here considered, denotes whatever is commanded by one who has a right to require obedience. A statute is a particular law drawn out in form, and distinctly enacted and proclaimed. Common law is a rule of action founded on long usage and the decisions of courts of justice. A regulation is a limited and often, temporary law, intended to secure some particular end or object. An edict is a command or law issued by a sovereign, and is peculiar to a despotic government. A decree is a permanent order either of a court or of the executive government. See Justice.

Webster's 1913 Dictionary

Periodic Pe`ri*od"ic, Periodical Pe`ri*od"ic*al, a. [L. periodicus, Gr. ?: cf. F. p['e]riodique.] 1. Of or pertaining to a period or periods, or to division by periods. The periodicaltimes of all the satellites. --Sir J. Herschel. 2. Performed in a period, or regular revolution; proceeding in a series of successive circuits; as, the periodical motion of the planets round the sun. 3. Happening, by revolution, at a stated time; returning regularly, after a certain period of time; acting, happening, or appearing, at fixed intervals; recurring; as, periodical epidemics. The periodic return of a plant's flowering. --Henslow. To influence opinion through the periodical press. --Courthope. 4. (Rhet.) Of or pertaining to a period; constituting a complete sentence. Periodic comet (Astron.), a comet that moves about the sun in an elliptic orbit; a comet that has been seen at two of its approaches to the sun. Periodic function (Math.), a function whose values recur at fixed intervals as the variable uniformly increases. The trigonomertic functions, as sin x, tan x, etc., are periodic functions. Exponential functions are also periodic, having an imaginary period, and the elliptic functions have not only a real but an imaginary period, and are hence called doubly periodic. Periodic law (Chem.), the generalization that the properties of the chemical elements are periodic functions of their atomic wieghts. ``In other words, if the elements are grouped in the order of their atomic weights, it will be found that nearly the same properties recur periodically throughout the entire series.'' The following tabular arrangement of the atomic weights shows the regular recurrence of groups (under I., II., III., IV., etc.), each consisting of members of the same natural family. The gaps in the table indicate the probable existence of unknown elements.