Hydrogen halides nonmetal hydrides

Nonmetals form covalent molecular hydrides, which consist of discrete molecules. These compounds are volatile and many are Bronstcd acids. Some are gases— for example, ammonia, the hydrogen halides (HF, HC1, HBr, HI), and the lighter hydrocarbons such as methane, ethane, ethene, and ethyne. Liquid molecular hydrides include water and hydrocarbons such as octane and benzene. 

A number of substances react vigorously with water, sometimes with the formation of hydrogen gas, which itself may ignite in the presence of air. Examples or such reactants are alkali metals, finely divided light metals and their hydrides, anhydrous metal oxides, anhydrous metal halides, nonmetal halides, and nonmetal oxides as well as certain organics such as anhydrides... 

Hydrogen reacts with nonmetals to form binary molecular hydrides. For example, H2 combines with the halogens to form colorless, gaseous hydrogen halides (Figure 6-5) ... 

Nitric acid, fuming Organic matter, nonmetals, most metals, ammonia, chlorosulfonic acid, chromium trioxide, cyanides, dichromates, hydrazines, hydrides, HCN, HI, hydrogen sulflde, sulfur dioxide, sulfur halides, sulfuric acid, flammable liquids and gases... 

Reacts with many metals to give hydrogen, sometimes violently. With non-metals pyrophoric hydrides may result. Frequently initiates explosive reactions between other substances. Violent reactions with many non-metal and some metal halides and oxyhalides, also with many organometallic compounds. Many metal nonmetal-lides produce toxic, flammable or pyrophoric gases on contact with diprotium monoxide. 

Water reactive materials are those that react violently with water. Alkali metals (e.g., hthium, sodium, and potassium), many organometallic compounds, and some hydrides react with water to produce heat and flammable hydrogen gas, which can ignite or combine explosively with atmospheric oxygen. Some anhydrous metal halides (e.g., aluminum bromide), oxides (e.g., calcium oxide), and nonmetal oxides (e.g., sulfur trioxide) and halides (e.g., phosphorus pentachloride) react exothermically with water, and the reaction can be violent if there is insufficient coolant water to dissipate the heat produced. 

The observation of electric transport in dense supercritical ionic phases stimulated the investigation of conductance in supercritical metals above 1500 °C and to pressures of about 2000 bar. The conductance of mercury was investigated and continuous metal-nonmetal transition was observed [25]. An impressive amount of further aspects of such metal-nonmetal transitions has been studied later in alkali metals and other fluids (see F. Hensel and coworkers) [25a]. A metal-nonmetal transition was also observed in cesium hydride and cesium in the liquid state at high hydrogen pressures [26] which corresponds to the earlier non-pressure work of Max Bredig [26a] with liquid metal-metal halide systems. 

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