More about Naming Compounds

Refer to the "Ions and Ionic Compounds" chapter for more about naming ionic compounds. 

Electrochemical techniques have been utilized for many years to study metal corrosion. Two of these techniques, linear polarization (LP) and cyclic voltammetry (CV), complement each other, LP providing corrosion rates under conditions where the surface is minimally altered and CV furnishing information about the corrosion mechanism. With the advent of impedance spectroscopy (IS), both kinds of information can be gleaned simultaneously and more rapidly, while leaving the surface almost intact. In this paper, we discuss the application of IS to the study of rapid steel corrosion and describe a study we undertook to elucidate the roles played by adsorption and film formation in the inhibition mechanisms of the above-named compounds. For comparison, we also investigated two quaternary nitrogen salts, which appear to adsorb electrostatically and presumably do not form macroscopic films (8). 

But how does one find a new class One way is to kind of stumble into it as a side-line of human experimentation with new psychedelics. But it is really difficult to pick up the clues as to what will be a good anti-depressant if you are not depressed. This compound, to which I had given the name of ARIADNE as the first of my ten classic ladies (I ll say more about them later), was not really a stimulant of any kind, certainly it was not a psychedelic, and yet there was something there. It had been explored rather extensively as a potential psychotherapeutic ally by a friend of mine. He said that there seemed to be some value in a few of his patients... 

Some types of ionic compounds can absorb water so that each formula unit is attached to a specific number of water molecules. They are called hydrates. Ba0H2 8H20 is called barium hydroxide octahydrate. CaS04 2H20 is called calcium sulfate dihydrate. Can you see the pattern Try naming MgS04 7H20. Use Table 3.8 to help you. You will learn more about hydrates in Chapter 6. 

Figure 3.6 shows 12 structures that may correspond to the abbreviation DPA. Six of them can be output by the ACD/Name to Structure software package, and six more were found by browsing the Internet. Note that even a specific context cannot guarantee an exact meaning. For example, both structures 3 and 8 were found in publications about coordination compounds. In general, chemical abbreviations are not unique and can rarely be distinguished from other trivial names except for the rather weak criterion that all letters are capitalized. We can conclude that conversion of any trivial name shorter than about five or six characters is not safe. A few rarer exceptions do exist, but this is a very short list. Examples include reserved abbreviations such as those for dimethyl sulfoxide (DMSO) and ethylenediaminetetraacetic acid, EDTA. 

Names based solely upon the empirical formulas are inadequate when more than one compound is known with the same empirical formula. This difficulty can be overcome where the substances in question have different molecular formulas. But many isomeric compounds of the same molecular weight gradually became known and it was also clear that names based simply upon empirical or molecular formulas were not very helpful. It was thus appreciated from the beginning of the modern chemical period and of modem chemical nomenclature that a satisfactory name for a chemical compound must tell something about its structure as well as about its composition. 

They are insoluble in water, which is why they form a distinct layer on a puddle of water. Hydrocarbons are less dense than water that s why the layer floats on top of the puddle. What causes the colorful effect The spill forms an extremely thin layer of hydrocarbon molecules on the water, which reflects sunlight. In this section, you will learn more about the structures and names of hydrocarbons, as well as the sources of these useful compounds. 

Since this is the book s first look at nomenclature, we limit ourselves to molecular binary compounds, those made up of only two elements, both nonmetals. Other binary compounds are named in Chapter 4, after you learn more about ions. Let s start by naming four molecular binary compounds to get an idea how names are formed, and then follow this with some rules. 

Other Names Many chemical compounds have more than one name. Compounds that have been known for many centuries often have common names that may still be used in industry, the arts, or some other field. For example, muriatic acid is a very old name for the compound now called hydrochloric acid. The name remains in common use today. Marine acid and spirit of salt are other ancient names for hydrochloric acid, but they are seldom used in the modern world. All compounds have systematic names, names based on a set of rules devised by the International Union of Pure and Applied Chemistry (IUPAC). For example, the systematic name for the poisonous gas whose common name is mustard gas is 2,2 -dichlorodiethyl sulfide. When chemists talk about chemical... 

Thiophene is the name for this sulfur-containing aromatic compound. There is more about it in Chapter 29. 

Kaolin or clay, its more common name, is a naturally occurring mineral with the chemical formula Al Si, 0, (OH)5. It has a plate-like structure, and is refined and treated for specific uses, the largest of which is the paper industry. Metakaolin, produced by the dehydroxylation of kaolin, is often used to improve the electrical properties of PVC wire and cable compounds. At loadings of about 30 weight percent of the resin in a wire and cable PVC formulation, a doubling of the volume resistivity can be achieved. 

A carboxylic acid with two COOH units is known as a dicarboxylic acid, or dioic acid. The molecule H02C-(CH2)3-C02H, for example, is named 1,5-pentanedioic acid. These compounds and more about the nomenclature of carboxylic acids are presented in Chapter 16 (Section 16.4). 

In fact Sm and Yb compounds are the only ones obeying the Luttinger criterion for Ef in the gap. The condition is that the lanthanide ions can exist in a divalent state 4f and 4f for Sm and Yb, respectively, with even number of electrons. In the intermediate-valent state due to hybridization, part of the 4f electrons obtain 5d character, but the sum of f and d electrons remains even. For other divalent lanthanide ions such as Eu or Tm with 4f or 4f states, respectively, the 4f count is odd. For Tm, however, an additional condition, namely anti ferromagnetic order has been found, which doubles the chemical unit cell and one arrives nevertheless at an even f and d electron count (more about this below, section 4.3). 

What about covalent compounds Covalent compounds are nonicmic, molecular compounds. For the most part, they contain only nonmetal atoms. A huge number of such compounds exist, and the naming schemes for these are much more involved than what we have seen for ionic compounds. The schemes we will study in this chapter are limited to compounds that contain only two nonmetals and compounds that are acids. Compounds, whether ionic or covalent, that contain just two elements are called binary compounds. Compounds, whether ionic or covalent, that contain three elements are called ternary compounds. The naming scheme for binary covalent compounds is discussed in Section 3.7. The naming scheme for acids, both binary and ternary, is discussed in Section 3.8. 

The majority of acids are ternary compounds. They contain three different elements—hydrogen and two other nonmetals. If one of the nonmetals is oxygen, the acid is called an oxoacid. Think of oxoacids as combinations of hydrogen ions (H ) and oxoanions. The scheme for naming oxoacids is similar to that outlined for oxoanions, except that the ending -ous is used instead of -ite and -ic instead of -ate. Several oxoacids are listed in Table 3.6. Also listed are the names and formulas of compounds in which the hydrogen of the oxoacid has been replaced by a metal, such as sodium. These compounds are called salts we will say much more about them in later chapters, beginning in Chapter 5. Acids are molecular compounds, and salts are ionic compoimds. 

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