Formulae arabic numerals

Stoichiometric Proportions. The stoichiometric proportions of the constituents in a formula may be denoted by Greek numerical prefixes mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- (Latin), deca-, undeca- (Latin), dodeca-,. . . , icosa- (20), henicosa- (21),. . . , tri-conta-(30), tetraconta-(40),. . . , hecta-(100), and so on, preceding without a hyphen the names of the elements to which they refer. The prefix mono can usually be omitted occasionally hemi-(1/2) and sesqui- (%) are used. No elisions are made when using numerical prefixes except in the case of icosa- when the letter i is elided in docosa- and tricosa-. Beyond 10, prefixes may be replaced by Arabic numerals. 

If we adopt the system of numbering each compd separately, and if the compd on the right side of the formula has simple arabic numerals (1,2,3, etc) counted clockwise, while the compd on the left side has primed arabic numerals 1, 2,3 etc, counted "counter-clockwise", then the formula may be represented as ... 

Roman numerals in names denote charges on ions Arabic numerals in formulas tell the number of atoms or ions present per formula unit. 

In CU2S, the two copper ions are balanced by one sulfide ion with a 2 charge the charge on each copper ion must be 1 +. In CuS, only one copper ion is present to balance the 2- charge on the sulfide ion the charge on the copper ion is 2 +. Note that the Roman numerals in the names of monatomic cations denote the charges on the ions. The Arabic numerals appearing as subscripts in formulas denote the number of atoms of that element present per formula unit. Either of these numbers can be used to deduce the other, but they are not the same ... 

A Roman numeral in parentheses in the name of the compound designates the charge on a cation and an Arabic numeral as a subscript in the formula designates the number of atoms or ions. The charges enable us to deduce the numbers of ions, and vice versa, but the Roman numerals and the Arabic numerals do not represent the same quantities. (Section 6.2)... 

Do not confuse oxidation numbers with charges when balancing oxidation-reduction equations. Use Roman numerals for pxrsitive oxidation numbers and Arabic numbers for charges. (To denote negative oxidation numbers, use Arabic numerals below the formula and circle them do not get them mixed up with charges. The Romans did not have negative numbers.)... 

Ans. (a) CU2S and (b) CuS. Nofe carefully that the Roman numerals in the names mean one thing—the charge on the ion—and the Arabic numeral subscripts in the formulas mean another—number of atoms. Here the copper(I) has a charge of 1 +, and therefore two copper(I) ions are required to balance the 2— charge on one sulfide ion. The copper(II) ion has a charge of 2+, and therefore one such ion is sufficient to balance the 2— charge on the sulfide ion. 

Ans. (a) Copper(II) oxide (b) copper(I) oxide. This example again emphasizes the difference between the Arabic numerals in a formula and the Roman numerals in a name. 

Arabic numerals are crucially important in nomenclature their placement in a formula or name is especially significant. 

In the formulae of addition compounds and compounds which can formally be regarded as such, including clathrates and multiple salts, a special format is used. The proportions of constituents are indicated by arabic numerals preceding the formulae of the constituents, and the formulae of the constituents are separated by a centre dot. The mles for ordering the constituent formulae are described in Section IR-4.4.3.5. 

Roman numerals in the names refer to the charge on the ion. Arabic numeral subscripts in the formula refer to the number of atoms. 

J) Bold-faced arabic numerals refer to formulae given in Tables. Italicised arabic numerals pertain to formulae in the running text. 

Algebra is a branch of mathematics that was invented by Greek mathematicians and developed by Hindu, Arab, and European mathematicians. It was apparently the first branch of symbolic mathematics. Its great utility comes from the fact that letters are used to represent constants and variables and that operations are indicated by symbols such as, x, /, and so on. Operations can be carried out symbolically instead of numerically so that formulas and equations can be modified and simplified before numerical calculations are carried out. This ability allows calculations to be carried out that arithmetic cannot handle. 

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