Pico-

Pico (unit symbol p) is a unit prefix in the metric system denoting a factor of one trillionth in the short scale and one billionth in the long scale (0.000000000001); that is, 10−12.

Derived from the Spanish word pico,[1] (peak, beak, little bit), pico is one of the original twelve prefixes defined in 1960 when the International System of Units (SI) was established.[2]

Atomic radii range from 28 picometers (pm) for helium to 260 pm for caesium. One picolight-year (ply) is about nine kilometers (six miles).[3]

Carbon atom has radius of 77 picometers.

PrefixBase 10 DecimalEnglish word Adoption[nb 1]Etymology
NameSymbolShort scaleLong scaleLanguageSource word
yottaY1024 1000000000000000000000000septillionquadrillion1991Latin eight[nb 2]
zettaZ1021 1000000000000000000000sextilliontrilliard1991Latinseven[nb 2]
exaE1018 1000000000000000000quintilliontrillion1975Greeksix
petaP1015 1000000000000000quadrillionbilliard1975Greekfive[nb 2]
teraT1012 1000000000000trillionbillion1960Greekfour,[nb 2] monster
gigaG109 1000000000billionmilliard1960Greekgiant
megaM106 1000000million1873Greekgreat
kilok103 1000thousand1795Greekthousand
hectoh102100 hundred1795Greekhundred
decada10110 ten1795Greekten
1001one
decid10−1 0.1tenth1795Latinten
centic10−2 0.01hundredth1795Latinhundred
millim10−3 0.001thousandth1795Latinthousand
microμ10−6 0.000001millionth1873Greeksmall
nanon10−9 0.000000001billionthmilliardth1960Greekdwarf
picop10−12 0.000000000001trillionthbillionth1960Spanishpeak, a little bit
femtof10−15 0.000000000000001quadrillionthbilliardth1964Danish fifteen, Fermi[nb 3]
attoa10−18 0.000000000000000001quintillionthtrillionth1964Danisheighteen
zeptoz10−21 0.000000000000000000001sextillionthtrilliardth1991Latinseven[nb 2]
yoctoy10−24 0.000000000000000000000001septillionthquadrillionth1991Latineight[nb 2]
  1. Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.
  2. Part of the beginning of the prefix was modified from the word it was derived from, ex: "peta" (prefix) vs "penta" (source word).
  3. The fermi was introduced earlier with the symbol "fm", which prompted the reinterpretation of the "f" as a prefix to "m", with femto being derived from the Danish word femten due to its similarity.

See also

References

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