Molecular substances binary compounds

Yet more important was the publication by Schottky and Wagner (1930) of their classical paper on the statistical thermodynamics of real crystals (41). This clarified the role of intrinsic lattice disorder as the equilibrium state of the stoichiometric crystal above 0° K. and led logically to the deduction that equilibrium between the crystal of an ordered mixed phase—i.e., a binary compound of ionic, covalent, or metallic type—and its components was statistical, not unique and determinate as is that of a molecular compound. As the consequence of a statistical thermodynamic theorem this proposition should be generally valid. The stoichiometrically ideal crystal has no special status, but the extent to which different substances may display a detectable variability of composition must depend on the energetics of each case—in particular, on the energetics of lattice disorder and of valence change. This point is taken up below, for it is fundamental to the problems that have to be considered. 

This very convincing use of Gay-Lussac s law and Avogadro s hypothesis by Cannizzaro quickly provided the chemical community with a direct way of establishing not only the molecular formulas of binary compounds but also the relative atomic masses of elements, starting with quantitative analytical data and the density of the appropriate gaseous substances. 

In the following pairs of binary compounds determine which one is a molecular substance and which one is an ionic... 

In the following pairs of binary compounds determine which one is a molecular substance and which one is an ionic substance. Use the appropriate naming convention (for ionic or molecular substances) to assign a name to each compound (a) SiF4 and LaF3, (b) FeCl2 and ReCls, (c) PbClj and RbCl. 

Bulk moduli for ambient conditions (with index o ) are listed in Tables 10.7 for elements, SlO.l for compounds MX, S10.2 for MX2, S10.3 for MX3, S10.4 for binary oxides, S10.5 for binary nitrides, S10.6 for binary borides, S10.7 for binary carbides and silicides, S10.8 for binary phosphides and arsenides, S10.9 for ternary oxides and coordination compounds, SIO.IO for molecular substances and polymers, SlO.l 1 for characteristics of polymorphous modifications of elements and the MX compounds, S10.12 for various phases ofMX2 crystals. 

Reactions of Oxygen Molecular oxygen is a very reactive gas and combines directly with many substances. The products are usually oxides. An oxide is a binary compound with oxygen in the —2 oxidation state. 

This book is divided into nine chapters. Chapter 1 describes the composition of polymer compounds and the chemical nature and physical properties of ingredients. Chapters 2 through 5 describe binary compounds of polymers with solid particles (Chapter 2), solvents (polymer solutions) (Chapter 3), additives such as stabilizers and curatives (Chapter 4), and a second polymer (blends) (Chapter 5). We turn to ternary compounds in Chapters 6 and 7. Chapter 6 discusses polymers with two low molecular weight liquids, two polymers with one low molecular weight substance, and three polymers including compatibilized polymer... 

We can often decide whether a substance is an ionic compound or a molecular compound by examining its formula. Binary molecular compounds are typically formed from two nonmetals (such as hydrogen and oxygen, the elements in water). Ionic compounds are typically formed from the combination of a metallic element with nonmetallic elements (such as the combination of potassium with sulfur and oxygen to form potassium sulfate, K2S04). Ionic compounds typically contain one metallic element the principal exceptions are compounds containing the ammonium ion, such as ammonium nitrate, which are ionic even though all the elements present are nonmetallic. 

Solution (a) The compound is named carbon disulfide, in analogy with the naming of ofher binary molecular compounds. (Section 2.8) (b) The substance will be listed as an inorganic compound. It contains no carbon-carbon bonds, nor any C—H bonds, which are fhe usual structural features of organic compounds, (c) Because CS2(s) consists of individual CS2 molecules, it would be a molecular solid in the classification scheme of Table 11.7. (d) The mosf likely producfs of the combustion will be CO2 and SO2. 

In this section, we discuss the nomenclature of some simple inorganic compounds. We hrst look at the naming of ionic compounds. Then, we look at the naming of some simple molecular compounds, including binary molecnlar componnds (molecular compounds of two elements) and acids. Finally, we look at hydrates of ionic compounds. These substances contain water molecules in loose association with ionic compounds. 

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