Period (periodic table)

In the periodic table of the elements, elements are arranged in a series of rows (or periods) so that those with similar properties appear in a column. Elements of the same period have the same number of electron shells; with each group across a period, the elements have one more proton and electron and become less metallic. This arrangement reflects the periodic recurrence of similar properties as the atomic number increases. For example, the alkaline metals lie in one group (group 1) and share similar properties, such as high reactivity and the tendency to lose one electron to arrive at a noble-gas electronic configuration. The periodic table of elements has a total of 118 elements.

Modern quantum mechanics explains these periodic trends in properties in terms of electron shells. As atomic number increases, shells fill with electrons in approximately the order shown at right. The filling of each shell corresponds to a row in the table.

In the s-block and p-block of the periodic table, elements within the same period generally do not exhibit trends and similarities in properties (vertical trends down groups are more significant). However in the d-block, trends across periods become significant, and in the f-block elements show a high degree of similarity across periods.

Period

Period may refer to:

Common meanings

Science and mathematics

Arts

Other uses

See also

Full stop

In punctuation, the full stop (Commonwealth English) or period (American English) is a punctuation mark placed at the end of a sentence. The full stop glyph is sometimes called a baseline dot because, typographically, it is a dot on the baseline. This term distinguishes the baseline dot from the interpunct (a raised dot).

The full stop glyph is also used for other purposes. It is often placed after an initial letter used to stand for a name, and sometimes placed after each individual letter in an initialism (for example, "U.S.A."; see Acronym#Punctuation). It also has multiple contexts in mathematics and computing, where it may be called dot or point (short for decimal point).

History

The full stop symbol derives from the Greek punctuation introduced by Aristophanes of Byzantium in the 3rd century BC. In his system, there were a series of dots whose placement determined their meaning. The full stop at the end of a completed thought or expression was marked by a high dot ⟨˙⟩, called the stigmḕ teleía (στιγμὴ τελεία) or "terminal dot". The "middle dot" ⟨·⟩, the stigmḕ mésē (στιγμὴ μέση), marked a division in a thought occasioning a longer breath (essentially a semicolon) and the low dot ⟨.⟩, called the hypostigmḕ (ὑποστιγμή) or "underdot", marked a division in a thought occasioning a shorter breath (essentially a comma). In practice, scribes mostly employed the full stop; the others fell out of use and were later replaced by other symbols. From the 9th century, the full stop began appearing as a low mark instead of a high one; by the advent of printing in Western Europe, the low mark was regular and then universal.

Period (Another American Lie)

Period (Another American Lie) is the debut studio album by B.A.L.L., released in 1987 by Shimmy Disc.

Track listing

All lyrics written by Don Fleming, all music composed by B.A.L.L..

Personnel

Adapted from the Period (Another American Lie) liner notes.

Release history

References