Chemistry (Chang), 9th Edition

Chapter 21: Nonmetallic Elements and Their Compounds

Chapter Summary

1. Hydrogen atoms contain one proton and one electron. They are the simplest atoms. Hydrogen combines with many metals and nonmetals to form hydrides; some hydrides are ionic and some are covalent.

2. There are three isotopes of hydrogen:

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Heavy water contains deuterium.

3. The important inorganic compounds of carbon are the carbides; the cyanides, most of which are extremely toxic; carbon monoxide, also toxic and a major air pollutant; the carbonates and bicarbonates; and carbon dioxide, an end product of metabolism and a component of the global carbon cycle.

4. Elemental nitrogen, N₂, contains a triple bond and is very stable. Compounds in which nitrogen has oxidation numbers from -3 to +5 are formed between nitrogen and hydrogen and/or oxygen atoms. Ammonia, NH₃, is widely used in fertilizers.

5. White phosphorus, P₄, is highly toxic, very reactive, and flammable; the polymeric red phosphorus, (P₄)_n, is more stable. Phosphorus forms oxides and halides with oxidation numbers of +3 and +5 and several oxoacids. The phosphates are the most important phosphorus compounds.

6. Elemental oxygen, O₂, is paramagnetic and contains two unpaired electrons. Oxygen forms ozone (O₃), oxides (O^2-), <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0035715985/117377/21_2.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (8.0K)</a> The most abundant element in Earth’s crust, oxygen is essential for life on Earth.

7. Sulfur is taken from Earth’s crust by the Frasch process as a molten liquid. Sulfur exists in a number of allotropic forms and has a variety of oxidation numbers in its compounds.

8. Sulfuric acid is the cornerstone of the chemical industry. It is produced from sulfur via sulfur dioxide and sulfur trioxide by means of the contact process.

9. The halogens are toxic and reactive elements that are found only in compounds with other elements. Fluorine and chlorine are strong oxidizing agents and are prepared by electrolysis.