Zepto prefix

In order to increase the precision of realization of the base unit meter, the definition based on the wavelength of a krypton-86 radiation was replaced in 1983 by one based on the speed of light. Also added were the prefixes zetta (Z) for 10, zepto (z) for 10 , yotta (Y) for 10 , and yocto (y) for 10 . 

Prefix deci- centi- milli- micro- nano- pico- fcmto- atto- zepto-... 

For example, if 1 pi of a 1 ppb solution (1 pg) is injected into a chromatograph, this will represent 10 femtomoles for a compound with a molecular weight of lOOg/mol The analyst must become accustomed to using prefixes that have seldom been used before femto- (1(T15), atto-(10-18), zepto- (10-21). Thus the zepto-mole contains only 602 molecules. These limits tend towards single atoms or molecules - the ultimate trace. 

One of the ways we will learn to express quantities in Chapter 1 is by using prefixes such as mega for million (I06), micro for one-millionth (10-6). and atto for 10-18. The illustration shows a signal due to light absorption by just 60 atoms of rubidium in the cross-sectional area of a laser beam. There are 6.02 X 1023 atoms in a mole, so 60 atoms amount to 1.0 X 10-22 moles. With prefixes from Table 1-3, we will express this number as 100 yoctomoles (ymol) or 0.1 zeptomole (zmol). The prefix yocto stands for I0-24 and zepto stands for 10-21. As chemists learn to measure fewer and fewer atoms or molecules, these strange-sounding prefixes become more and more common in the chemical literature. 

Table C Metric Multipliers tera, peta, exa come from tetra, penta, hexa with one letter removed zetta, yotta come from zeta, iota, with one letter added atto comes from Danish "atten" for 18 zepto comes from Latin "septem" or Greek "hepta" (1000 7) and yocto comes from Greek "octo" (1000-8) with one prefix letter added...

By way of example, if IpiL of a Ippb solution (being about Ipg), is injected into a chromatograph, and if a mole of the analyte weighs 100 g, this will be 10 femtomol From this point the analyst must become familiarized with prefixes such as femto- (10 ), atto- (10 ), zepto- (10 ). Azeptomole contains only 602 molecules of a given compound. These quantities tend towards single atoms or individual molecules. The ultimate trace is almost attained. 

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