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:
“It is noticed, that the consideration of the great periods and spaces of astronomy induces a dignity of mind, and an indifference to death.”
—Ralph Waldo Emerson (1803–1882)
“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)
“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)