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:
“Those who weep for the happy periods which they encounter in history acknowledge what they want; not the alleviation but the silencing of misery.”
—Albert Camus (1913–1960)
“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)
“Whose are the truly labored sentences? From the weak and flimsy periods of the politician and literary man, we are glad to turn even to the description of work, the simple record of the month’s labor in the farmer’s almanac, to restore our tone and spirits.”
—Henry David Thoreau (1817–1862)