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Mosquitoes, common smaller species (about 2.5 milligrams), [53] grain of salt or sand, [54] medicines are typically expressed in milligrams [55] 10 −5 centigram (cg) 1.1 × 10 −5 kg Small granule of quartz (2 mm diameter, 11 milligrams) [56] 2 × 10 −5 kg Adult housefly (Musca domestica, 21.4 milligrams) [57] 10 −4 decigram (dg) 0.27 ...
The Green Book is a direct successor of the Manual of Symbols and Terminology for Physicochemical Quantities and Units, originally prepared for publication on behalf of IUPAC's Physical Chemistry Division by M. L. McGlashen in 1969. A full history of the Green Book's various editions is provided in the historical introduction to the third edition.
The prefix symbols are always prepended to the symbol for the unit without any intervening space or punctuation. [9] This distinguishes a prefixed unit symbol from the product of unit symbols, for which a space or mid-height dot as separator is required. So, for instance, while 'ms' means millisecond, 'm s' or 'm·s' means metre-second.
The official symbol for the SI prefix micro is a Greek lowercase mu (μ). [7] For reasons stemming from its design, Unicode has two different character codes for the letter, with slightly different appearance in some fonts, although most fonts use the same glyph.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.
Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements; but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols , normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.
Unit prefixes that are much larger or smaller than encountered in practice are seldom used, albeit valid combinations. In most contexts only a few, the most common, combinations are established. For example, prefixes for multiples greater than one thousand are rarely applied to the gram or metre.
"The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10 12 Hz , K cd , to be 683 when expressed in the unit lm W −1 , which is equal to cd sr W −1 , or cd sr kg −1 m −2 s 3 , where the ...