Periods
Seven periods of elements occur naturally on Earth. For period 8, which includes elements which may be synthesized after 2011, see the extended periodic table.
A group in chemistry means a family of objects with similarities like different families.
Read more about this topic: Period (periodic Table)
Famous quotes containing the word periods:
“The History of the world is not the theatre of happiness. Periods of happiness are blank pages in it, for they are periods of harmony—periods when the antithesis is in abeyance.”
—Georg Wilhelm Friedrich Hegel (1770–1831)
“How easily and cleverly do I write just now! I am really pleased with myself; words come skipping to me like lambs upon Moffat Hill; and I turn my periods smoothly and imperceptibly like a skilful wheelwright turning tops in a turning-loom. There’s fancy! There’s simile!”
—James Boswell (1740–1795)
“Compared to football, baseball is almost an Oriental game, minimizing individual stardom, requiring a wide range of aggressive and defensive skills, and filled with long periods of inaction and irresolution. It has no time limitations. Football, on the other hand, has immediate goals, resolution on every single play, and a lot of violence—itself a highlight. It has clearly distinguishable hierarchies: heroes and drones.”
—Jerry Mander, U.S. advertising executive, author. Four Arguments for the Elimination of Television, ch. 15, Morrow (1978)