Chemical formulas formula units

A formula unit of a substance is the group represented by the substance s chemical formula, that is, a group containing the kinds and numbers of atoms or ions listed in the chemical formula. Formula unit is a general term that can be used in reference to elements, molecular compounds, or ionic compounds. One formula unit of the noble gas neon, Ne, contains one neon atom. In this case, the formula unit is an atom. One formula unit of water, Ff20, contains two hydrogen atoms and one oxygen atom. In this case, the formula unit is a molecule. One formula unit of ammonium chloride,... 

Molecule Chemical formula Formula weight Temperature Radiation, wavelength Crystal system, space group Unit cell parameters... 

A CIF file is given below for hexamethylbenzene. Information includes chemical formula, formula weight, lattice constants, volume of unit cell, information from the International Tables for Crystallography, fractional coordinates of the individual atoms, and thermal parameters. ... 

Another example of deahng with molecular structure input/output can be found in the early 1980s in Boehiinger Ingelheim. Their CBF (Chemical and Biology Facts) system [44] contained a special microprocessormolecular structures. Moreover, their IBM-type printer chain unit had been equipped with special chemical characters and it was able to print chemical formulas. 

Exact numbers, such as the stoichiometric coefficients in a chemical formula or reaction, and unit conversion factors, have an infinite number of significant figures. A mole of CaCb, for example, contains exactly two moles of chloride and one mole of calcium. In the equality... 

Normality is the number of equivalent weights (EW) per unit volume and, like formality, is independent of speciation. An equivalent weight is defined as the ratio of a chemical species formula weight (FW) to the number of its equivalents... 

Polystyrene [9003-53-6] (PS), the parent of the styrene plastics family, is a high molecular weight linear polymer which, for commercial uses, consists of - 1000 styrene units. Its chemical formula (1), where n = - 1000, tells htde of its properties. 

Stearic acid is a member of the group called fatty acids. These are hydrocarbon chains (chains made of repeated units of a carbon atom and two hydrogen atoms) with a carboxyl group at one end. A carboxyl group is the COOH in the chemical formula. It is what turns the hydrocarbon chain into an organic acid. 

The chemical formula of a compound represents its composition in terms of chemical symbols. Subscripts show the numbers of atoms of each element present in the smallest unit that is representative of the compound. For molecular compounds, it is common to give the molecular formula, a chemical formula that shows how many atoms of each type of element are present in a single molecule of the compound. For instance, the molecular formula for water is H20 each molecule contains one O atom and two H atoms. The molecular formula for estrone, a female sex hormone, is Clgl-I2202, showing that a single molecule of estrone consists of 18 C atoms, 22 FI atoms, and 2 O atoms. A molecule of a male sex hormone, testosterone, differs by only a few atoms its molecular formula is (lyH2802. Think of the consequences of that tiny difference ... 

The chemical formula of an ionic compound shows the ratio of the numbers of atoms of each element present in one formula unit. A formula unit of an ionic compound is a group of ions with the same number of atoms of each element as appears in its formula. 

STRATEGY When Ba(OH)2 dissolves in water, it provides OH ions most hydroxides of Groups 1 and 2 can be treated as fully dissociated in solution. Decide from the chemical formula how many OH ions are provided by each formula unit and calculate the concentrations of these ions in the solution. To find the concentration of H,Oj ions, use the water autoprotolysis constant Kw = [H,0 1 [OH ]. 

However, it is best to use the full chemical equation when working with titrations to ensure the correct stoichiometry. For example, if hydrochloric acid is used to neutralize Ca(OH)2, we must take into account the fact that each formula unit of Ca(OH)2 provides two OH ions ... 

Bearing in mind that the relative sizes of the ions permit isomorphous replacement of OH by F but not by Cl, we write with considerable confidence the formula (Si, Al, Fe, P)18O20(OH, F)laCl, which agrees well with analyses 1, 2, and 3. Inasmuch as aluminium (as well as phosphorus) may replace silicon with coordination number 4, it is evident that there are at least five silicon atoms in the unit, corresponding to the chemical formula... 

The large size of the unit of structure and the complexity of the chemical formula make the deduction of the atomic arrangement from X-ray data alone impractical if not impossible. We consequently make use also of arguments based on analogy with other structures, semi-empirical structural rules regarding ionic sizes and ionic environments, etc., with ultimate recourse to the stochastic1) method, which has already... 

Barke, H. D., Wirbs, H. (2002). Structural units and chemical formulae chemistry education. Research and Practice in Europe, 3, 185-200. 

Quite often, molecules have the same chemical formula but differ in their structures. For example, two compounds have the chemical formula C2 Hg O (Figure 3-2b and c). Dimethyl ether has a C—O—C linkage, while ethanol contains C—O—H. To distinguish between these two different substances, chemists write the formula of dimethyl ether as CH3 OCH3 and the formula of ethanol as CH3 CH2 OH. The first formula indicates that the molecule has two CH3 units linked to an oxygen atom. The second formula tells us that there is a C2 H5 unit attached to an OH group. Molecules that have the same molecular formula but different arrangements of atoms are called isomers. 

There are many different polyatomic anions, including several that are abundant in nature. Each is a stable chemical species that maintains its stmcture in the solid state and in aqueous solution. Polyatomic anions are treated as distinct units when writing chemical formulas, naming compounds, or drawing molecular pictures. The names, formulas, and charges of the more common polyatomic anions are listed in Table 3-4. You should memorize the common polyatomic ions because they appear regularly throughout this textbook. 

Many ionic compounds can have water molecules incorporated into their solid structures. Such compounds are called hydrates. To emphasize the presence of discrete water molecules in the chemical structure, the formula of any hydrate shows the waters of hydration separated from the rest of the chemical formula by a dot. A coefficient before H2 O indicates the number of water molecules in the formula. Copper(II) sulfate pentahydrate is a good example. The formula of this beautiful deep blue solid is C11SO4 5 H2 O, indicating that five water molecules are associated with each CuSOq unit. Upon prolonged heating, CuSOq 5 H2 O loses its waters of hydration along with its color. Other examples of hydrates include aluminum nitrate nonahydrate, A1 (N03)3 9 H2 O,... 

One mole of any chemical compound is one mole of its chemical formula unit. Here are some examples ... 

The chemical formula of a compound contains essential information about its composition. The formula identifies which elements are present, and it states the number of atoms of each kind present in one unit of the compound. We need the chemical formula of a substance to calculate its molar mass. In fact, almost all chemical calculations require the correct chemical formula. How are chemical formulas determined in the first place ... 

Begin by finding the chemical formula from the name, nickel(II) chloride hexahydrate. Chloride ion carries -1 charge, and the (II) indicates that nickel is a +2 cation. Electrical neutrality requires two chlorides for every nickel. The name also tells us that the salt contains six water molecules for each unit of nickel(II) chloride. Thus, each formula unit of the salt contains one cation, two Cl anions,... 

C03-0131. The seventh-ranked industrial chemical in U.S. production is phosphoric acid, whose chemical formula is H3 PO4. One method of manufacture starts with elemental phosphoms, which is burned in air the product of this reaction then reacts with water to give the final product. In 1995, the United States manufactured 2.619 X 10 pounds of phosphoric acid. How many moles is this If 15% of this material was made by burning elemental phosphoms, how many moles and how many kilograms of phosphoms were consumed ... 

In the usual chemical formulas written for chain polymers the sue-cessive units are projected as a co-linear sequence on the surface of the sheet of paper. This form of representation fails to convey what is perhaps the most significant structural characteristic of a long polymer chain, namely, its capacity to assume an enormous array of configurations. This configurational versatility is a consequence of the considerable degree of rotational freedom about single bonds of the chain. In the simple polymethylene chain, for example, the conventional formula... 

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