Monatomic anions

Increasing the negative charge of an anion increases its basicity, while increasing the number of oxo groups decreases its basicity (since this increases the size and the number of electronegative atoms in the anion). Monatomic and oxo anions can thus be classified as in Table 3. 

Cumulative errors incurred in such calculations mean that only values of Astruc5 (X )>20 J moU indicate that the ion is definitely water structurebreaking and only values <-20 J K moU indicate it to be structure-making. In between values designate the ions to be borderline cases. This treatment could be applied to nearly 150 aqueous cations and anions, monatomic and polyatomic, with charges — 4 < zi < 4. The linear correlation with the viscosity B, (except for tetraalkylammonium cations) is ... 

Ion, cation, anion, monatomic ion, polyatomic ion, acid anion... 

Naming ionic compounds In naming ionic compounds, name the cation first, then the anion. Monatomic cations use the element name. Monatomic anions use the root of the element name plus the suffix -ide. If an element can have more than one oxidation number, use a Roman numeral in parentheses after the element name, for example, iron(II) to indicate the Fe ion. For polyatomic ions, use the name of the ion. 

See Secs. 3.1.2.2 and 3.1.2.8 for naming monatomic and certain polyatomic anions. When an organic group occurs in an inorganic compound, organic nomenclature (q.v.) is followed to name the organic part. 

A particularly imaginative application of this concept has led to the isolation of compounds which contain monatomic alkali metal anions. For example, Na was reacted with cryptand in the presence of EtNHi to give the first example of a sodide salt of... 

The Ga analogue was prepared similarly. The planar anions are embedded between columns of condensed icosahedra (Cs6K6/2) which in turn are centred by the remaining unique monatomic Sb anion. 

Metals form cations nonmetals form anions C, P, and the metalloids do not form monatomic ions. 

Nearly all cations are monatomic the majority of anions are polyatomic. 

Monatomic anions are named by adding the suffix -ide to the stem of the name of the nonmetal from which they are derived. 

FIGURE C.7 The typical monatomic anions formed by a selection of elements in the periodic table. Notice how the charge on each ion depends on its group number. Only the nonmetals form monatomic anions under common conditions. 

Monatomic anions, such as the Cl- ions in sodium chloride and the O2- ions in quicklime (CaO), are named by adding the suffix -ide and the word ion to the first part of the name of the element (the stem" of its name), as shown in Table D.l thus, S2 is a sulfide ion and O2 is an oxide ion. There is usually no need to specify the charge, because most elements that form monatomic anions form only one kind of ion. The ions formed by the halogens are collectively called halide ions and include fluoride (F ), chloride (Cl-), bromide (Br-), and iodide (I ) ions. 

Names of monatomic anions end in -ide. Oxoanions are anions that contain oxygen. The suffix -ate indicates a greater number of oxygen atoms titan the suffixe -ite within the same series of oxoanions. 

Step 3 If the anion is monatomic, change the ending of the element s name to -ide. 

To predict the electron configuration of a monatomic cation, remove outermost electrons in the order np, ns, and (n — l)d fora monatomic anion, add electrons until the next noble-gas configuration has been reached. The transfer of electrons results in the formation of an octet (or duplet) of electrons in the valence shell on each of the atoms metals achieve an octet (or duplet) by electron loss and nonmetals achieve it by electron gain. 

Formulas of compounds consisting of the monatomic ions of main-group elements can be predicted by assuming that cations have lost all their valence electrons and anions have gained electrons in their valence shells until each ion has an octet of electrons, ora duplet in the case of FI, Li, and Be. 

All ionic bonds have some covalent character. To see how covalent character can arise, consider a monatomic anion (such as Cl-) next to a cation (such as Na+). As the cation s positive charge pulls on the anion s electrons, the spherical electron... 

Carbon is the only Group 14/IV element that forms both monatomic and polyatomic anions. There are three classes of carbides saline carbides (saltlike carbides), covalent carbides, and interstitial carbides. The heavier elements in Group 14/IV form polyatomic anions, such as Si44 and Sn52, in which the atoms form a tetrahedron and trigonal bipyramid, respectively. 

A number of general features in Table 1-3 is apparent. Complexes may be cationic, neutral or anionic. Ligands may be simple monatomic ions, or larger molecules or ions. Many ligands are found as related neutral and anionic species (for example, water, hydroxide and oxide). Complexes may contain all of the same type of ligand, in which case they are termed homoleptic, or they may contain a variety of ligand types, whereby they are described as heteroleptic. Some ligands such as nitrite or thiocyanate can coordinate to a metal ion in more than one way. This is described as ambidentate behaviour. In such cases, we commonly indicate... 

Whereas many metals form monatomic cations, only six nonmetallic elements commonly form anions. 

The cations are significantly smaller than the anions in most 1 1 ionic salts, but cesium, which forms the largest monatomic cation, is an exception. Because its cations and anions are close to the same size, cesium chloride is most stable in a body-centered cubic lattice. There are Cl anions at the comers of the cube, with a Cs in the... 

Monatomic cations with constant charges Monatomic cations with variable charges Polyatomic cations Monatomic anions Oxyanions... 

Common anions may be grouped as follows monatomic anions, oxyanions, and special anions. There are special endings for the first two groups the third group is small enough to be memorized. 

If the anion is monatomic (has one atom), the name of the element is amended by changing the... 

The charge on every monatomic anion is equal to the group number minus 8 (or 18, if the most modern periodic table group numbering system is used). 

What is the difference in the rules for remembering charges on monatomic anions and oyxanions ... 

Figure 9.3 shows the relationship between ionic radius and proton affinity in a graphical way for monatomic ions having a — 1 charge. It is clear that to a good approximation there is a correlation between the size of the anion and its proton affinity. While this is in no way a detailed study, it is clear that the smaller (and thus harder] the negative ion (with the same type of structure) the more strongly it binds a proton. 

A Schottky defect in a crystal consists of a cation and anion vacancy combination that ensures overall electroneutrality in the crystal (Section 1.9). The estimation of the configurational entropy change in creating a population of Schottky defects in a crystal can be obtained in the same way as that of a population of vacancies in a monatomic crystal. The method follows that given in Section 2.1 for the equilibrium concentration of vacancies in a monatomic crystal and is set out in detail in Supplementary Material S4. 

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