Compound formula example

Class FunctlonsI Group Molecular Formula Example Compound Name... 

Rather similar was the paper [PolG36a] which also derives asymptotic formulae for the number of several kinds of chemical compounds, for example the alcohols and benzene and naphthalene derivatives. Unlike the paper previously mentioned, this one gives proofs of the recursion formulae from which the asymptotic results are derived. A third paper on this topic [PolG36] covers the same sort of ground but ranges more broadly over the chemical compounds. Derivatives of anthracene, pyrene, phenanthrene, and thiophene are considered as well as primary, secondary, and tertiary alcohols, esters, and ketones. In this paper Polya addresses the question of enumerating stereoisomers -- a topic to which we shall return later. 

Calculate the mass percentage of an element in a compound from a formula (Example El). 

Vacant M site V" Divalent ions are chosen as an example, with MX as the compound formula... 

When a free element reacts with a compound of different elements, the free element will replace one of the elements in the compound if the free element is more reactive than the element it replaces. In general, a free metal will replace the metal in the compound, or a free nonmetal will replace the nonmetal in the compound. A new compound and a new free element are produced. As usual, the formulas of the products are written on the bases presented in Chap. 5. The formula of a product does not depend on the formula of the reacting element or compound. For example, consider the reactions... 

The two most common series of chromium halides have the formulas CrX2 and CrX3 (where X = F, Cl, Br, or I). However, CrF6 is also known. Compounds having the formula CrX3 are Lewis acids, and they also form many coordination compounds. For example, CrX3 reacts with liquid ammonia to yield... 

Although the compounds [Pt(en)2Cl2]Br2 and [Pt(en)2Br2]Cl2 have the same empirical formulas, they are quite different compounds. For example, the first gives Br- when dissolved in water, whereas the second gives Cl-. This occurs because in the first case, the Cl- ions are coordinated to the Pt4+, whereas in the second case the Br- ions are coordinated to the metal ion. The isomerism in cases such as these is known as ionization isomerism. It is easy to see that many pairs of compounds could be considered as ionization isomers, among them the following examples ... 

The formula unit of a compound is a group of atoms that has atoms of the same type and number as are present in the formula of that compound. For example, if Na2 appears in the formula of the compound, then there will be two sodium atoms in the formula unit of that compound. 

Have you ever wondered how to draw the structures of compounds For example, compounds such as CCI4, PBr3 or ions such as SO. To draw the structural formulae we will use the Lewis (electron dot) notation. 

Let s use the following compounds as examples CS2, C1F3, and N205. You should locate the elements in each compound on the periodic table to confirm the order they appear in the formula. The next step is to write the name of each element in the same order that they appear in the formula ... 

If the formula of a compound is known, it is a fairly straightforward task to determine the percent composition of each element in the compound. For example, suppose you want to calculate the percentage hydrogen and oxygen in water, H20. First calculate the molecular mass of water ... 

Powders are thorough mixtures of dry, finely divided drugs and exeipients that are intended for internal or external use. Granules are dosage forms that eonsist of parti-eles ranging in size from about 4 to 10 mesh (2000-4750 pm). Both powders and granules are easy to use and to compound. An example formula of a eurrently compounded powder ineludes the following ... 

The simplest formula for an organic compound is called its empirical formula. This shows the elements present in the compound and the simplest ratio of the atoms of these elements in the compound. For example, ethane (C H ) has an empirical formula of CHj, whereas benzene (C H ) has an empirical formula of CH. Empirical formulae can be determined by a technique known as elemental microanalysis and you will find out more about this on p. 72. 

There are general formulas for other oxygen compounds. For example, alcohols can be generalized as R-OH, aldehydes as R-CHO, and carboxyhc acids as R-COOH. 

Because Dalton did not know the chemical formula for compounds, he assumed the greatest simplicity. This worked fine for some compounds such as CO or NO, but introduced error for other compounds, for example, assuming water was HO. Nevertheless, Dalton s ideas laid the foundation for the modern atomic theory. Dalton s ideas briefly summarized are ... 

We can use Lewis dot formulas to represent the transfer of electrons in the formation of ionic compounds. For example, the formation of the ionic compound sodium fluoride, NaF, can be represented using Lewis dot formulas and valence electron conflgurations ... 

Group General Formula Compound Class Example... 

Translating a formula into a name is equally simple. All you need to do is convert the subscripts into prefixes and attach them to the names of the elements that make up the compound. For example, for the compound N20, you simply attach the prefix di- to nitrogen to indicate the two nitrogen atoms and tetra- to oxygen to indicate the four oxygen atoms, giving you dinitrogen tetroxide. 

A rather similar effect can occur with the formation of nonstoichiometric compounds. For example, copperfl) sulfide may not have the exact ratio of 2 1 expected from the formula. Cu2S. Some of the Cu ions may be absent if they are compensated by an equivalent number of Cu2+ ions. Since both Cu and Cu2 ions are stable, it... 

Important as the molecular formula is. it does not describe fully the properties, or even in some cases the identity, of chemical compounds. For example, there are two compounds that have the molecular formula CjFLO. They are different in all their properties, both chemical and physical. This difference is due to a difference in the manner in which the atoms are connected in the molecules of the two substances. These differences can be shown only by the use of structural formulas, such as those shown in Fig. I, in which the valence bonds between the atom are shown. These structural formulas are determined circumstantially, lhat is. by the chemical reactions into which the compounds enter. (However, (heir arrangements have been confirmed In many cases by a direci instrumental means such us speclrometric methods, x-ray studies, etc.) These reactions differ markedly for ethyl alcohol and methyl ether. Such compounds which have the same molecular formula but differ due to the arrangements or positions of their atoms are called isomers, and the type just cited, in which the difference is in the grouping of the atoms, are called functional isomers. These, and many other lypes of isomers, are treated in the entry on Isomerism. 

The molar masses of molecular and ionic compounds are calculated from the molar masses of the elements present the molar mass of a compound is the sum of the molar masses of the elements that make up the molecule or the formula unit. We need only note how many times each atom or ion appears in the molecular formula or the formula unit of the ionic compound. For example, the molar mass of the ionic compound Na2S04 is... 

If we have 1 mole of a compound, then the formula shows the number of moles of each element in that compound. For example, the formula for lead(n) bromide is PbBr2. This means that 1 mole of lead(n) bromide contains 1 mole of lead ions and 2 moles of bromide ions. If we do not know the formula of a compound, we can find the masses of the elements present experimentally and these masses can be used to work out the formula of that compound. 

Structural isomerism is when the molecules differ in the sequence of atomic attachments in the skeleton of the molecule. The compounds in Example 1 are structural isomers. The IUPAC names clearly state the difference between compounds with the same molecular formula, but different structures. 

If no direct measurement of the fluorescence lifetime is available the relations between the radiative lifetime and the fluorescence and absorption spectra can be used in conjunction with the quantum yield to obtain an indication of the fluorescence lifetime. Birks and Munro (1967) have reviewed the methods of calculating the radiative lifetime. In general these methods are limited to specific groups of compounds. For example, Favaro et al. (1973) applied Stickler and Berg s (1962) formula to the spectral data obtained from an excited state acid-base study of some styrylpyridines and found a lack of quantitative agreement between the measured and calculated lifetimes. 

Empirical formula Simplest whole-number formula expressing the composition of a chemical compound. For example, the empirical formula for the sesquiterpene bisabolene is C.Hg, while its molecular formula is three times that, giving C15H24. 

Molecular formula The formula that expresses the numbers of each constituent element atom present in one molecule of a compound. For example, geraniol has 10 carbon atoms, 18 hydrogens and 1 oxygen, so its molecular formula is C10HlgO. 

Another arena in which topologically restrained molecules are of importance involves endothelial compounds for example, a small molecule or ion inside a fisular cage, such as a fullerene. The first of these to be discovered occurred when Diedrich et al. [5] doped C60 with potassium to encapsulate 3 potassium atoms inside the cage. The systemic name for this compound would now be formed by augmenting the name for fullerene that had been developed earlier in Formulas (42) or (43) of Chapter 3 with a semicolon, followed by a zero numbered locant branch e.g., °(K,K,K) — assuming that the three potassium atoms are independent of one another i.e.,... 

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