Element order binary compounds

For binary compounds the name of the element standing later in the sequence in Sec. 3.1.1.3 is modified to end in -ide. Elements other than those in the sequence of Sec. 3.1.1.3 are taken in the reverse order of the following sequence, and the name of the element occurring last is modified to end in -ide e.g., calcium stannide. 

The written name of a compound includes the names of the elements it contains and information about the numbers of atoms of each element. The elements have to occur in some order, and this order is set by the same guidelines as for the chemical formula (see Section 3-11. Names can contain element names, roots derived from element names, and prefixes indicating the number of atoms of each element. Tables and 3 list the more important roots and prefixes that appear in the names of binaiy compounds. We can summarize the rules for naming binary compounds in three guidelines ... 

In a similar way, electrochemistry may provide an atomic level control over the deposit, using electric potential (rather than temperature) to restrict deposition of elements. A surface electrochemical reaction limited in this manner is merely underpotential deposition (UPD see Sect. 4.3 for a detailed discussion). In ECALE, thin films of chemical compounds are formed, an atomic layer at a time, by using UPD, in a cycle thus, the formation of a binary compound involves the oxidative UPD of one element and the reductive UPD of another. The potential for the former should be negative of that used for the latter in order for the deposit to remain stable while the other component elements are being deposited. Practically, this sequential deposition is implemented by using a dual bath system or a flow cell, so as to alternately expose an electrode surface to different electrolytes. When conditions are well defined, the electrolytic layers are prone to grow two dimensionally rather than three dimensionally. ECALE requires the definition of precise experimental conditions, such as potentials, reactants, concentration, pH, charge-time, which are strictly dependent on the particular compound one wants to form, and the substrate as well. The problems with this technique are that the electrode is required to be rinsed after each UPD deposition, which may result in loss of potential control, deposit reproducibility problems, and waste of time and solution. Automated deposition systems have been developed as an attempt to overcome these problems. 

The first compounds to be discussed will be compounds of two nonmetals. These binary compounds are named with the element to the left or below in the periodic table named first. The other element is then named, with its ending changed to -ide and a prefix added to denote the number of atoms of that element present. If one of the elements is to the left and the other below, the one to the left is named first unless that element is oxygen or fluorine, in which case it is named last. The same order of elements is used in writing formulas for these compounds. (The element with the lower electronegativity is usually named first refer to Table 5-1.) The prefixes are presented in Table 6-2. The first six prefixes are the most important to memorize. 

The relationships between bond enthalpy, bond length and bond order which appear relatively simple in the case of a main group element such as carbon and its compounds, are more difficult to establish when the d-transition metal elements and their compounds are considered. Progress in establishing these relationships for metals is severely hindered by a lack of relevant thermochemical data. This paper reviews some of the more useful information that is available for diatomic molecules, for polynuclear binary carbonyls and for binuclear complexes of the d-transition elements. 

Quantitative analysis of the surface composition from the intensity of the peaks requires the quantification factors to be known. As with the peak position, it is possible to use reference compounds in order to determine these factors (taking care to correct for any surface segregation that might modify the observed composition compared to the expected composition). A series of carefully chosen binary compounds can be used to establish relative sensitivity factors for a large number of elements (Fig, 5.6). 

Chemical nomenclature deals with names of elements and their combinations. Whereas writing the symbol or the name of an element is straightforward, a choice of which element to write first in the formula and in the name has to be made as soon as an element is associated with one or more other elements to form, for example, a binary compound. The order of citation of elements in formulae and names is based upon the methods outlined below. Furthermore, groups of atoms, such as ions, ligands in coordination compounds and substituent groups in derivatives of parent hydrides, are ordered according to specified rules. 

Many binary compounds, especially halides and oxides of elements, may be made in this direct way, although there are limitations. It is clear that the formation of the desired compound AB must be thermodynamically favourable. There may also be kinetic problems, and the above synthesis of LiH requires a temperature of 600°C in order to overcome the activation energy associated with breaking the H-H bond. In some cases the reaction may be facilitated by using a catalyst, as in the synthesis of ammonia from H2 and N2 (see Topics H5 and J5). 

Binary compounds are named in the customary manner, with the more electropositive part of the name first, in the case of both salts and nonsalts. Since no order of decreasing electropositivity for nonmetallic elements is provided... 

In order to obtain useful photoemission at photon energies lower than the threshold of Cs, it would seem necessary simply to find a metallic compound alloy in which the electron work function is lower than the 2eV elemental minimum (but there is none), or to find a semiconductor where Ef + X<2eV. This search has led to the discovery of the classical photoemissive compounds. The binary compound with the lowest electron affinity is cesium antimonide, CsjSb, where X=0.45 eV [5.39]. Here Eq 1.6 eV for a threshold c Eq + X of about 2 eV. For the more complex substance (NaKCsSb), which is not actually a true compound but is rather (NaKSb) with a surface skin of (NaKCsSb) [5.40],... 

A binary compound is a compound composed of only two elements. Binary compounds composed of a metal and a nonmetal are usually ionic and are named as ionic compounds, as we have just discussed. (For example, NaCl, MgBr2, and AI2N3 are all binary ionic compounds.) Binary compounds composed of two nonmetals or metalloids are usually molecular and are named using a prefix system. Examples of binary molecular compounds are H2O, NH3, and CCI4. Using this prefix system, you name the two elements using the order given by the formula of the compound. 

When we earlier doped elementary or binary compounds the reaction was fairly straightforward. When we dope a ternary or higher compound, however, the reaction may be less obvious - we have some choices. It is quite common, however, to do the synthesis and write the equation in such a way that one takes out a corresponding amount of the host element that is substituted. If we, for instance, want to dope LaScOa with Ca substituting for La, we go for a composition Lai-xCaxScOs. In order to see how we write the doping reaction in this case we first just look at the trivial normal synthesis ... 

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