<p> Chapter 1</p><p>The “Elemental” Foundation of Chemistry: Atoms, Molecules, Elements, Compounds, Mixtures, and States of Matter</p><p>Review Questions</p><p>1. The subject of chemistry is primarily concerned with matter and its transformations.</p><p>2. Both b and c are correct. Characteristic properties of metals include ductility, and conductivity. Since metals are malleable (they can be molded into shapes without fracturing), they are not brittle.</p><p>3. The three other characteristic properties not mentioned in question 2 are the luster, opaqueness, and malleability associated with metals.</p><p>4. Several metals were discussed in the text. These include gold (Au), silver (Ag), iron (Fe), aluminum (Al), tin (Sn), palladium (Pd), cadmium (Cd), vanadium (V), cesium (Cs), copper (Cu), lead (Pb), chromium (Cr), nickel (Ni), zinc (Zn), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), barium (Ba), radium (Ra), and mercury (Hg).</p><p>Non-metals discussed in the text include: sulfur (S), hydrogen (H), helium (He), carbon (C), nitrogen (N), oxygen (O), fluorine (F), neon (Ne), silicon (Si), phosphorus (P), chlorine (Cl), argon (Ar), radon (Rn), bromine (Br), and iodine (I).</p><p>5. Nanotechnology is an area of modern scientific engineering concerned with developing very small devices able to manipulate matter one atom at a time. Current goals include the assembly of microscopic computers and hand-held machines for the diagnosis of disease.</p><p>6. A pure substance is matter composed exclusively of one element or compound.</p><p>7. No, the characteristics of a compound are not the same as those of its elemental components. For example, the properties of water are radically different from its component elements, hydrogen and oxygen.</p><p>8. Metalloids are elements that exhibit properties characteristic of both metals and non- metals.</p><p>9. Mixtures that have a uniform composition throughout are called homogeneous. Those that do not have a uniform composition are called hetrogeneous.</p><p>1 10. Colloids are heterogeneous mixtures composed of two or more types of materials, one of which is finely divided and suspended or dispersed in the other. Homogenized milk, composed of small fat particles suspended in a watery substance, is an example of a colloid. Other types of colloids include a solid dispersed in a gas (smoke - an aerosol), a solid dispersed in a liquid (paint - a sol), a solid dispersed in a solid (steel - a solid sol), a liquid dispersed in a gas (fog - an aerosol), a liquid dispersed in a solid (jelly – a gel), a gas dispersed in a liquid (whipped cream – a foam), and a gas dispersed in a solid (ice cream – solid foam).</p><p>11. Emulsions are colloids composed of two liquids. Gels are a colloid composed of a liquid dispersed in a solid. Milk and mayonnaise are examples of emulsions. Jelly and shaving preparations are examples of gels.</p><p>12. An emulsifying agent is a substance that is soluble in both of the materials composing an emulsion, thereby acting as a stabilizer. An example of an emulsifying agent is the egg yolk in mayonnaise. </p><p>13. The three states of matter are solids, liquids, and gases. Ice, water, and steam are examples of a solid, liquid, and gas, respectively. In our bodies, common examples of solids include bone, teeth, hair, skin, muscle, tendons, and cartilage. Blood and body fluids are examples of liquids, and oxygen and carbon dioxide are examples of gases that enter and leave your lungs when you breathe. </p><p>14. In both solids and liquids, the component atoms lie close together. As a result, both solids and liquids are difficult to compress. The volume occupied by a liquid is not much greater than the corresponding volume of its solid state. </p><p>Solids and liquids have one key difference. In a solid, the component particles are, on average, “fixed” in their position. In contrast, the component particles of a liquid move past each other. </p><p>15. Unlike the component particles of solids and liquids, particles of a gas lie, on average, a great distance from each other. As most of the space in a gas is completely empty of gas particles, the volume occupied by a sample of matter in the gaseous state is much greater than the volume of the sample when it exists as either a solid or a liquid.</p><p>16. A condensed state of matter is one characterized by a high mass-to-volume ratio. The two common condensed states of matter are solids and liquids, as they are much denser than gases.</p><p>17. Gases are composed of independent tiny particles that rapidly travel through empty space in a straight line. Because of the rapid motion of its component particles, a gas quickly expands to fill the allowable volume. Gas particles can change direction when they collide with either the walls of the container or other gas particles.</p><p>2 18. Pressure is defined as the force exerted by a gas on a specified area of a surface.</p><p>19. Atoms are minute, spherical particles that are indivisible. (They cannot be split into two or more identical parts.) During a chemical change, atoms can be neither created nor destroyed. </p><p>Molecules are collections of atoms that are bound to each other. Molecules remain intact upon melting or boiling.</p><p>20. Molecules that consist of two atoms are called diatomic molecules. The two atoms can be either identical or different. Several examples are given below.</p><p>Identical atoms:</p><p> hydrogen – H2 fluorine – F2</p><p> chlorine – Cl2 bromine – Br2</p><p> iodine – I2 nitrogen – N2</p><p> oxygen – O2</p><p>Different atoms:</p><p> carbon monoxide – CO nitrogen monoxide – NO</p><p>21. Molecules that consist of more than two atoms are called polyatomic mole-cules. The component atoms can be either identical or different. Several examples are given below.</p><p>Identical atoms:</p><p> gaseous phosphorus – P4 ozone – O3</p><p>Different atoms:</p><p> water – H2O carbon dioxide – CO2</p><p> ammonia – NH3 sucrose – C12H22O11</p><p>22. The chemical formula of a molecule indicates both the type and number of the component atoms. This elemental composition is given by the symbol for each atom followed by a numerical subscript indicating the number of that type of atom present in one molecule.</p><p>3 23. a) There are two hydrogen atoms in one molecule of hydrogen.</p><p> b) There are two oxygen atoms in one molecule of oxygen.</p><p> c) There are two hydrogen atoms and one oxygen atom in one molecule of water.</p><p>24. From the formula for glucose, you can tell that one molecule is composed of six atoms of carbon, twelve atoms of hydrogen, and six atoms of oxygen.</p><p>25. Mercury is known to attack the brain, resulting in mental and physiological disturbances. Nickel and copper in jewelry react with sweat and frequently produce black, rust-colored, or green discolorations on the skin. Individuals with a sensitivity to nickel often develop rashes when exposed to tiny amounts of the metal.</p><p>26. Mercury is found in several places in the environment. Common sources include the incineration of waste and sewage sludge, the burning of fuels, and electrical components, such as light switches. </p><p>27. Both mercury vapor and water soluble mercury compounds (those that dissolve in water) are highly toxic.</p><p>Symptoms of mercury poisoning range from mild mental and physiological disturbances to vomiting, coughing up blood, breathing difficulties, and seizures. Long-term exposure has been known to cause uncontrollable twitching, incoherent speech, and drooling.</p><p>28. Alloys are mixtures of metals.</p><p>29. Interstitial alloys are alloys in which the small atoms of one of the component elements fit in the spaces between the rows of the major metal. This results in the “hardening” of the major metallic component by reducing the “sliding” movement of atoms.</p><p>30. Alloys formed when atoms of the minority metal replace some of the atoms in the regular structure of the majority metal are called substitutional alloys. These alloys have a uniform composition and, thus, are classified as solutions. </p><p>Examples of substitutional alloys include brass (an alloy of zinc in copper), bronze (an alloy of tin and lead in copper), and coinage metals (various alloys of gold, silver, copper, and nickel).</p><p>31. An amalgam is an alloy of two or more metals, one of which is mercury. </p><p>Dental amalgams consist of mercury, silver, tin, copper, and zinc.</p><p>4 32. a) Gold (Au) is an element.</p><p> b) Bronze is an alloy of metals, such as tin and lead, in copper.</p><p> c) Silver (Ag) is an element.</p><p> d) Brass is an alloy of zinc in copper.</p><p>33. Compounds are materials that consist of two or more types of atoms in a fixed ratio. Compounds have a uniform composition throughout their structure and cannot easily be separated into their component elements. Substitutional alloys, while having a uniform composition throughout, can vary in their composition of component elements. Additionally, the pure components of an alloy can be recovered by melting the alloy and separating the layers.</p><p>Mixtures contain pure substances in no fixed proportions. Alloys can be either classified as homogeneous mixtures (solutions) or heterogeneous mixtures (solder, for example). While the percentage of each component of an alloy can vary, elemental compositions are generally limited to certain ranges. </p><p>34. a) Examples of compounds include table salt (sodium chloride, NaCl), glucose (C6H12O6), and sucrose (C12H22O11).</p><p> b) Examples of mixtures include coffee with sugar completely dissolved in it (a homogeneous mixture) and granite rock (a heterogeneous mixture).</p><p> c) Examples of alloys include brass (an alloy of zinc in copper), bronze (an alloy of tin and lead in copper) and mercury amalgams (an alloy of mercury, silver, copper, and zinc).</p><p>35. The carat system is used to classify alloys of gold and is based on the number 24. Pure gold is called 24-carat, and an alloy of 50% gold (by mass) is known as 12-carat gold. The simple formula to calculate the number of carats of gold in a gold alloy is:</p><p> carats of gold = 24 x fraction of gold (by mass) in the sample</p><p> or</p><p> carats of gold = 24 x (mass of gold in the sample / total mass of the sample)</p><p>36. Other elements commonly included in gold alloys are silver, copper, and nickel.</p><p>5 Understanding Concepts</p><p>37. Metals are ductile (able to be drawn into wire) and malleable (able to be hammered into sheets or other shapes without fracturing) because the component atoms in metals can be easily and readily displaced relative to each other.</p><p>38. a) Elements are the fundamental types of matter. Elements can not be split into two or more stable components by chemical means. Compounds consist of two or more elements in a fixed ratio. Compounds cannot easily be separated into their components.</p><p> b) Mixtures, unlike compounds, contain substances in no fixed proportions. In addition, since the components of the mixture are not held together by strong forces, it is often easy to separate the constituents of a mixture. Finally, the properties of compounds are different from those of its component elements, whereas the properties of mixtures often represent an average of the properties of its constituents.</p><p>39. a) White sugar is a compound, sucrose, with the chemical formula C12H22O11. White sugar is a compound because it is the same everywhere in the world (elements are combined in a fixed ratio) and it is difficult to separate white sugar into its component elements, carbon, hydrogen, and oxygen.</p><p> b) Your skin is a heterogeneous mixture. Skin is composed of numerous cells containing elements, compounds, and other substances in varying proportions. Using sophisticated biochemical techniques, scientists are able to easily separate several of the components of skin cells.</p><p> c) Wood is also a heterogeneous mixture. Similar to skin, wood is composed to numerous plant cells containing elements, compounds, and other substances in varying proportions.</p><p> d) Nickel is an element with the symbol Ni. Nickel cannot be split into two or more stable components by chemical means.</p><p> e) Salty water is a solution composed of one or more salts dissolved in water. When the salt is fully dissolved, the mixture has a uniform composition throughout and is called homogeneous. </p><p> f) A well-stirred mixture of salt and pepper is a heterogeneous mixture. Even though it is well stirred, the mixture does not have uniform properties or composition throughout.</p><p>40. A mixture of pure alcohol and water would be termed a solution. Since the two components can be mixed in any proportion, it cannot be a compound. (Remember that the constituents of compounds exist in a fixed ratio). Also, compounds are composed of elements, and alcohol and water are both compounds. </p><p>6 41. Air is a heterogeneous mixture. Air is primarily composed of two molecules, nitrogen gas and oxygen gas in a ratio of about 78:21. Additionally, the combination of gases to form air does not result in the substantial loss or gain of energy. Thus, air can be neither a pure substance (a substance composed of one particular element or compound) nor a compound (matter composed of elements in a fixed ratio whose formation involves fundamental changes at the atomic level). Since air can contain other materials, such as organic matter and nitrates, it lacks a uniform composition throughout and is, therefore, correctly classified as a homogeneous mixture.</p><p>42. a) Smog is a heterogeneous mixture consisting of air, other gases, and solid particulate matter. As it is composed of compounds in no specific ratio, it cannot be classified as either an element or a compound. Since it contains small solid particles, it cannot be a solution, or homogeneous mixture.</p><p> b) Helium gas is an element with the symbol He. Helium cannot be split into two or more stable components by chemical means.</p><p> c) Soup is a heterogeneous mixture. It is composed of substances in varying proportions, its formation is not accompanied by significant changes in energy, and it does not have a uniform composition throughout.</p><p> d) Cream is a heterogeneous mixture. It is also composed of substances, such as fats, proteins, and sugars, in varying proportions. Its formation is not accompanied by significant changes in energy and it does not have a uniform composition throughout.</p><p> e) Pure copper wire is an element with the symbol Cu. Copper cannot be split into two or more stable components by chemical means.</p><p> f) Soil is a heterogeneous mixture. It is composed of several compounds and substances, such as quartz, limestone, and decaying organic matter in varying proportions. The combination of these materials to make soil is not associated with a large gain or loss of energy. Since some soils are “richer” in organic materials than others, it does not have a uniform composition throughout.</p><p> g) Oil-and-vinegar salad dressing is also a heterogeneous mixture. Various ratios of oil and vinegar can be used to make this dressing, and the components easily separate upon standing.</p><p>7 43. a) H2O2</p><p> b) CH4</p><p> c) Br2</p><p> d) C2H6O</p><p>44. C12H22O11</p><p>45. No, a colloid is not an emulsion. An emulsion is a special type of colloid in which both of the components are liquids. Therefore, all emulsions are colloids, but all colloids are not emulsions.</p><p>46. The terms crystalline and amorphous refer to the arrangement of particles in a given solid. When a large number of particles are regularly arranged, that is, the particles are located equidistant from the neighboring particles, a crystalline structure is formed. When the arrangement of particles in a solid is much less ordered, then the material is called amorphous.</p><p>47. a) An element having an extended network:</p><p>● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●</p><p> b) A pure substance composed of diatomic molecules:</p><p>●● ●● ●● ●●</p><p> c) A pure substance composed of polyatomic molecules:</p><p>●○● ●○● ●○● ●○●</p><p> d) A solution composed of two molecular substances:</p><p>●●● ●●● ●● ●●● ●●● ●● ●●●</p><p>8 e) A heterogeneous mixture of two molecular substances:</p><p>●● ●● ●● ●● ●● ●●</p><p>48. When a molecular substance is in a liquid crystal state, it has physical properties that are intermediate between those of a solid and a liquid. The particles that make up a solid are fixed in location and exhibit little movement. Additionally, in a crystalline solid, the particles are arranged in a highly ordered fashion. This is contrasted with the particles of a liquid, which are less ordered in structure, are not fixed in location, and exhibit moderate movement. Substances in a liquid crystal state flow like a viscous liquid (liquids with some resistance to flow), but have molecules that exist in highly ordered patterns. </p><p>49. Author’s Note: The following information was obtained from the website of the United States Environmental Protection Agency and www.delta-institute. org/publication/Steel-Hg-Report-0627011.pdf. </p><p>The information provided represents known mercury toxins. Other forms of mercury, +2 such as Hg2 salts and other organomercury compounds may result from the burning of coal, garbage, and medical waste.</p><p> a) Hg0, Hg+2, Hg(particulate) b) Hg0, Hg+2, Hg(particulate) c) Hg0, Hg+2, mercury amalgams d) Hg0, Hg+2 e) Hg0, Hg+2, Hg(particulate)</p><p>50. Author’s Note: The following information was obtained from the website of the United States Environmental Protection Agency and www.delta-institute. org/publication/Steel-Hg-Report-0627011.pdf. The information provided represents known mercury toxins. Other forms of mercury, +2 such as Hg2 salts and other organomercury compounds may exist in air, water, or food.</p><p>0 +2 + a) air contains: Hg , Hg , Hg(particulate), (CH3)Hg , and (CH3)2Hg 0 +2 + b) water contains: Hg , Hg , (CH3)Hg , and (CH3)2Hg 0 +2 + c) food contains: Hg , Hg , CH3)Hg , and (CH3)2Hg</p><p>9 51. To solve this problem use the formula:</p><p> carats of gold = 24 x fraction of gold (by mass) in the sample</p><p>The gold alloy is 70% gold, so the fraction of gold (by mass) in the sample is 0.70.</p><p> carats of gold = 24 x 0.70 = 16.8 or 17 carats</p><p>52. To determine the percent (%) gold, divide the number of carats in the gold alloy by 24 and then multiply by 100 to convert the fraction of gold to a percentage. We can represent this operation mathematically as follows:</p><p> the percentage of gold = fraction of gold x 100</p><p> and</p><p> the fraction of gold = carats in gold alloy / 24</p><p> therefore,</p><p> the percentage of gold = (carats in gold alloy / 24) x 100</p><p> a) 24-carat gold </p><p> the percentage of gold = (carats in gold alloy / 24) x 100</p><p>= (24 / 24) x 100</p><p>= 100%</p><p> b) 20-carat gold</p><p> the percentage of gold = (carats in gold alloy / 24) x 100</p><p>= (20 / 24) x 100</p><p>= 83%</p><p> c) 12-carat gold</p><p> the percentage of gold = (carats in gold alloy / 24) x 100</p><p>= (12 /24) x 100</p><p>= 50%</p><p>10 Synthesizing Ideas</p><p>53. Table 1.2 in the text lists the names, symbols, and atomic numbers for the elements. Although the atoms of different elements vary slightly in size, they all occupy generally the same volume. It is, therefore, reasonable to conclude that atoms with a larger atomic number are more dense. Since the atomic numbers of aluminum and lead are 13 and 82, respectively, 100 atoms of lead would weigh more than 100 atoms of aluminum. This conclusion is verified by our everyday experiences with these two metals. </p><p>54. Ideally, dental fillings should be mechanically strong, but not brittle. They should not tarnish, and they should have the appearance and texture of real teeth.</p><p>55. The information on fish consumption advisories was obtained from United States Environmental Protection Web site and the Minnesota Pollution Control Agency Web site. It is important to note that these recommendations are dependent upon the specific lake, the location within the lake, the type and size of fish, and the gender and health of the consumer. Additionally, other toxins, such as PCBs (polychlorinated biphenyls) have been found in several species of fish in the Great Lakes. As these recommendations are generalizations and represent conditions in a changing environment, current local, state, and federal guidelines should be examined prior to consumption.</p><p>The form of mercury most likely to be found in sport fish is methyl mercury. Current guidelines indicate that a health adult male can consume 52 fish per year (one per week). As previously noted, these are general guidelines based on methyl mercury, and they to not consider other potential toxic materials in the fish.</p><p>11</p>