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<title>The History of the Periodic Table</title>
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<div class="section" id="averill_1.0-ch07_s01" condition="start-of-chunk" version="5.0" lang="en">
<h2 class="title editable block">
<span class="title-prefix">7.1</span> The History of the Periodic Table</h2>
<div class="learning_objectives editable block" id="averill_1.0-ch07_s01_n01">
<h3 class="title">Learning Objective</h3>
<ol class="orderedlist" id="averill_1.0-ch07_s01_l01">
<li>To become familiar with the history of the periodic table.</li>
</ol>
</div>
<p class="para editable block" id="averill_1.0-ch07_s01_p01">The modern periodic table has evolved through a long history of attempts by chemists to arrange the elements according to their properties as an aid in predicting chemical behavior. One of the first to suggest such an arrangement was the German chemist Johannes Dobereiner (1780–1849), who noticed that many of the known elements could be grouped in <span class="margin_term"><a class="glossterm">triads</a><span class="glossdef">A set of three elements that have similar properties.</span></span>, sets of three elements that have similar properties—for example, chlorine, bromine, and iodine; or copper, silver, and gold. Dobereiner proposed that all elements could be grouped in such triads, but subsequent attempts to expand his concept were unsuccessful. We now know that portions of the periodic table—the <em class="emphasis">d</em> block in particular—contain triads of elements with substantial similarities. The middle three members of most of the other columns, such as sulfur, selenium, and tellurium in group 16 or aluminum, gallium, and indium in group 13, also have remarkably similar chemistry.</p>
<p class="para editable block" id="averill_1.0-ch07_s01_p02">By the mid-19th century, the atomic masses of many of the elements had been determined. The English chemist John Newlands (1838–1898), hypothesizing that the chemistry of the elements might be related to their masses, arranged the known elements in order of increasing atomic mass and discovered that every seventh element had similar properties (<a class="xref" href="#averill_1.0-ch07_s01_f01">Figure 7.1 "The Arrangement of the Elements into Octaves as Proposed by Newlands"</a>). (The noble gases were still unknown.) Newlands therefore suggested that the elements could be classified into <span class="margin_term"><a class="glossterm">octaves</a><span class="glossdef">A group of seven elements, corresponding to the horizontal rows in the main group elements (not counting the noble gases, which were unknown at the time).</span></span>, corresponding to the <em class="emphasis">horizontal</em> rows in the main group elements. Unfortunately, Newlands’s “law of octaves” did not seem to work for elements heavier than calcium, and his idea was publicly ridiculed. At one scientific meeting, Newlands was asked why he didn’t arrange the elements in alphabetical order instead of by atomic mass, since that would make just as much sense! Actually, Newlands was on the right track—with only a few exceptions, atomic mass does increase with atomic number, and similar properties occur every time a set of <em class="emphasis">ns</em><sup class="superscript">2</sup><em class="emphasis">np</em><sup class="superscript">6</sup> subshells is filled. Despite the fact that Newlands’s table had no logical place for the <em class="emphasis">d</em>-block elements, he was honored for his idea by the Royal Society of London in 1887.</p>
<div class="callout editable block" id="averill_1.0-ch07_s01_n02">
<h3 class="title">John Newlands (1838–1898)</h3>
<p class="para" id="averill_1.0-ch07_s01_p03">Newlands noticed that elemental properties repeated every seventh (or multiple of seven) element, as musical notes repeat every eighth note.</p>
</div>
<div class="figure large medium-height editable block" id="averill_1.0-ch07_s01_f01">
<p class="title"><span class="title-prefix">Figure 7.1</span> The Arrangement of the Elements into Octaves as Proposed by Newlands</p>
<img src="section_11/47ac12052be3cf634c25a07efc388f94.jpg">
<p class="para">The table shown here accompanied a letter from a 27-year-old Newlands to the editor of the journal <em class="emphasis">Chemical News</em> in which he wrote: “If the elements are arranged in the order of their equivalents, with a few slight transpositions, as in the accompanying table, it will be observed that elements belonging to the same group usually appear on the same horizontal line. It will also be seen that the numbers of analogous elements generally differ either by 7 or by some multiple of seven; in other words, members of the same group stand to each other in the same relation as the extremities of one or more octaves in music. Thus, in the nitrogen group, between nitrogen and phosphorus there are 7 elements; between phosphorus and arsenic, 14; between arsenic and antimony, 14; and lastly, between antimony and bismuth, 14 also. This peculiar relationship I propose to provisionally term the <em class="emphasis">Law of Octaves</em>. I am, &c. John A. R. Newlands, F.C.S. Laboratory, 19, Great St. Helen’s, E.C., August 8, 1865.”</p>
</div>
<p class="para editable block" id="averill_1.0-ch07_s01_p04">The periodic table achieved its modern form through the work of the German chemist Julius Lothar Meyer (1830–1895) and the Russian chemist Dimitri Mendeleev (1834–1907), both of whom focused on the relationships between atomic mass and various physical and chemical properties. In 1869, they independently proposed essentially identical arrangements of the elements. Meyer aligned the elements in his table according to periodic variations in simple atomic properties, such as “atomic volume” (<a class="xref" href="#averill_1.0-ch07_s01_f02">Figure 7.2 "Variation of Atomic Volume with Atomic Number, Adapted from Meyer’s Plot of 1870"</a>), which he obtained by dividing the atomic mass (molar mass) in grams per mole by the density of the element in grams per cubic centimeter. This property is equivalent to what is today defined as <span class="margin_term"><a class="glossterm">molar volume</a><span class="glossdef">The molar mass of an element divided by its density.</span></span> (measured in cubic centimeters per mole):</p>
<div class="equation block" id="averill_1.0-ch07_s01_eq01">
<p class="title editable"><span class="title-prefix">Equation 7.1</span> </p>
<math xml:id="averill_1.0-ch07_m001" display="block">
<semantics>
<mrow>
<mfrac>
<mrow>
<mtext>molar mass (</mtext>
<menclose notation="updiagonalstrike">
<mtext>g</mtext>
</menclose>
<mtext>/mol</mtext>
<mo stretchy="false">)</mo>
</mrow>
<mrow>
<mtext>density (</mtext>
<menclose notation="updiagonalstrike">
<mtext>g</mtext>
</menclose>
<msup>
<mrow>
<mtext>/cm</mtext>
</mrow>
<mn>3</mn>
</msup>
<mo stretchy="false">)</mo>
</mrow>
</mfrac>
<mo>=</mo>
<msup>
<mrow>
<mtext>molar volume (cm</mtext>
</mrow>
<mn>3</mn>
</msup>
<mtext>/mol</mtext>
<mo stretchy="false">)</mo>
</mrow>
</semantics>
</math>
</div>
<p class="para editable block" id="averill_1.0-ch07_s01_p05">As shown in <a class="xref" href="#averill_1.0-ch07_s01_f02">Figure 7.2 "Variation of Atomic Volume with Atomic Number, Adapted from Meyer’s Plot of 1870"</a>, the alkali metals have the highest molar volumes of the solid elements. In Meyer’s plot of atomic volume versus atomic mass, the nonmetals occur on the rising portion of the graph, and metals occur at the peaks, in the valleys, and on the downslopes.</p>
<div class="callout editable block" id="averill_1.0-ch07_s01_n03">
<h3 class="title">Dimitri Mendeleev (1834–1907)</h3>
<p class="para" id="averill_1.0-ch07_s01_p06">When his family’s glass factory was destroyed by fire, Mendeleev moved to St. Petersburg, Russia, to study science. He became ill and was not expected to recover, but he finished his PhD with the help of his professors and fellow students. In addition to the periodic table, another of Mendeleev’s contributions to science was an outstanding textbook, <em class="emphasis">The Principles of Chemistry</em>, which was used for many years.</p>
</div>
<div class="figure large medium-height editable block" id="averill_1.0-ch07_s01_f02">
<p class="title"><span class="title-prefix">Figure 7.2</span> Variation of Atomic Volume with Atomic Number, Adapted from Meyer’s Plot of 1870</p>
<img src="section_11/cc303c3ea24f0273307cac2a4504f2f4.jpg">
<p class="para">Note the periodic increase and decrease in atomic volume. Because the noble gases had not yet been discovered at the time this graph was formulated, the peaks correspond to the alkali metals (group 1).</p>
</div>
<div class="section" id="averill_1.0-ch07_s01_s01">
<h2 class="title editable block">Mendeleev’s Periodic Table</h2>
<p class="para editable block" id="averill_1.0-ch07_s01_s01_p01">Mendeleev, who first published his periodic table in 1869 (<a class="xref" href="#averill_1.0-ch07_s01_s01_f01">Figure 7.3 "Mendeleev’s Periodic Table, as Published in the German Journal "</a>), is usually credited with the origin of the modern periodic table. The key difference between his arrangement of the elements and that of Meyer and others is that Mendeleev did not assume that all the elements had been discovered (actually, only about two-thirds of the naturally occurring elements were known at the time). Instead, he deliberately left blanks in his table at atomic masses 44, 68, 72, and 100, in the expectation that elements with those atomic masses would be discovered. Those blanks correspond to the elements we now know as scandium, gallium, germanium, and technetium.</p>
<div class="figure large editable block" id="averill_1.0-ch07_s01_s01_f01">
<p class="title"><span class="title-prefix">Figure 7.3</span> Mendeleev’s Periodic Table, as Published in the German Journal <em class="emphasis bolditalic">Annalen der Chemie und Pharmacie</em> in 1872</p>
<img src="section_11/a07f44b64f16216b3a2ff6fedf27abe6.jpg">
<p class="para">The column headings “Reihen” and “Gruppe” are German for “row” and “group.” Formulas indicate the type of compounds formed by each group, with “R” standing for “any element” and superscripts used where we now use subscripts. Atomic masses are shown after equal signs and increase across each row from left to right.</p>
</div>
<p class="para editable block" id="averill_1.0-ch07_s01_s01_p02">The most convincing evidence in support of Mendeleev’s arrangement of the elements was the discovery of two previously unknown elements whose properties closely corresponded with his predictions (<a class="xref" href="#averill_1.0-ch07_s01_s01_t01">Table 7.1 "Comparison of the Properties Predicted by Mendeleev in 1869 for "</a>). Two of the blanks Mendeleev had left in his original table were below aluminum and silicon, awaiting the discovery of two as-yet-unknown elements, <em class="emphasis">eka</em>-aluminum and <em class="emphasis">eka</em>-silicon (from the Sanskrit <em class="emphasis">eka</em>, meaning “one,” as in “one beyond aluminum”). The observed properties of gallium and germanium matched those of <em class="emphasis">eka</em>-aluminum and <em class="emphasis">eka</em>-silicon so well that once they were discovered, Mendeleev’s periodic table rapidly gained acceptance.</p>
<div class="table block" id="averill_1.0-ch07_s01_s01_t01" frame="all">
<p class="title"><span class="title-prefix">Table 7.1</span> Comparison of the Properties Predicted by Mendeleev in 1869 for <em class="emphasis bolditalic">eka</em>-Aluminum and <em class="emphasis bolditalic">eka</em>-Silicon with the Properties of Gallium (Discovered in 1875) and Germanium (Discovered in 1886)</p>
<table cellpadding="0" cellspacing="0">
<thead>
<tr>
<th align="center">Property</th>
<th align="center">
<em class="emphasis">eka</em>-Aluminum (predicted)</th>
<th align="center">Gallium (observed)</th>
<th align="center">
<em class="emphasis">eka</em>-Silicon (predicted)</th>
<th align="center">Germanium (observed)</th>
</tr>
</thead>
<tbody>
<tr>
<td>atomic mass</td>
<td>68</td>
<td>69.723</td>
<td>72</td>
<td>72.64</td>
</tr>
<tr>
<td rowspan="3">element</td>
<td>metal</td>
<td>metal</td>
<td>dirty-gray metal</td>
<td>gray-white metal</td>
</tr>
<tr>
<td>low mp*</td>
<td>mp = 29.8°C</td>
<td>high mp</td>
<td>mp = 938°C</td>
</tr>
<tr>
<td>
<em class="emphasis">d</em> = 5.9 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 5.91 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 5.5 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 5.323 g/cm<sup class="superscript">3</sup>
</td>
</tr>
<tr>
<td rowspan="2">oxide</td>
<td>E<sub class="subscript">2</sub>O<sub class="subscript">3</sub>
</td>
<td>Ga<sub class="subscript">2</sub>O<sub class="subscript">3</sub>
</td>
<td>EO<sub class="subscript">2</sub>
</td>
<td>GeO<sub class="subscript">2</sub>
</td>
</tr>
<tr>
<td>
<em class="emphasis">d</em> = 5.5 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 6.0 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 4.7 g/cm<sup class="superscript">3</sup>
</td>
<td>
<em class="emphasis">d</em> = 4.25 g/cm<sup class="superscript">3</sup>
</td>
</tr>
<tr>
<td rowspan="2">chloride</td>
<td>ECl<sub class="subscript">3</sub>
</td>
<td>GaCl<sub class="subscript">3</sub>
</td>
<td>ECl<sub class="subscript">4</sub>
</td>
<td>GeCl<sub class="subscript">4</sub>
</td>
</tr>
<tr>
<td>volatile</td>
<td>
<p class="para">mp = 78°C</p>
<p class="para">bp* = 201°C</p>
</td>
<td>bp < 100°C</td>
<td>bp = 87°C</td>
</tr>
</tbody>
<tfoot>
<tr>
<th colspan="5">*mp = melting point; bp = boiling point.</th>
</tr>
</tfoot>
</table>
</div>
<p class="para editable block" id="averill_1.0-ch07_s01_s01_p03">When the chemical properties of an element suggested that it might have been assigned the wrong place in earlier tables, Mendeleev carefully reexamined its atomic mass. He discovered, for example, that the atomic masses previously reported for beryllium, indium, and uranium were incorrect. The atomic mass of indium had originally been reported as 75.6, based on an assumed stoichiometry of InO for its oxide. If this atomic mass were correct, then indium would have to be placed in the middle of the nonmetals, between arsenic (atomic mass 75) and selenium (atomic mass 78). Because elemental indium is a silvery-white <em class="emphasis">metal</em>, however, Mendeleev postulated that the stoichiometry of its oxide was really In<sub class="subscript">2</sub>O<sub class="subscript">3</sub> rather than InO. This would mean that indium’s atomic mass was actually 113, placing the element between two other metals, cadmium and tin.</p>
<p class="para editable block" id="averill_1.0-ch07_s01_s01_p04">One group of elements that is absent from Mendeleev’s table is the noble gases, all of which were discovered more than 20 years later, between 1894 and 1898, by Sir William Ramsay (1852–1916; Nobel Prize in Chemistry 1904). Initially, Ramsay did not know where to place these elements in the periodic table. Argon, the first to be discovered, had an atomic mass of 40. This was greater than chlorine’s and comparable to that of potassium, so Ramsay, using the same kind of reasoning as Mendeleev, decided to place the noble gases between the halogens and the alkali metals.</p>
</div>
<div class="section" id="averill_1.0-ch07_s01_s02">
<h2 class="title editable block">The Role of the Atomic Number in the Periodic Table</h2>
<p class="para editable block" id="averill_1.0-ch07_s01_s02_p01">Despite its usefulness, Mendeleev’s periodic table was based entirely on empirical observation supported by very little understanding. It was not until 1913, when a young British physicist, H. G. J. Moseley (1887–1915), while analyzing the frequencies of x-rays emitted by the elements, discovered that the underlying foundation of the order of the elements was by the <em class="emphasis">atomic number</em>, not the atomic mass. Moseley hypothesized that the placement of each element in his series corresponded to its atomic number <em class="emphasis">Z</em>, which is the number of positive charges (protons) in its nucleus. Argon, for example, although having an atomic mass greater than that of potassium (39.9 amu versus 39.1 amu, respectively), was placed <em class="emphasis">before</em> potassium in the periodic table. While analyzing the frequencies of the emitted x-rays, Moseley noticed that the atomic number of argon is 18, whereas that of potassium is 19, which indicated that they were indeed placed correctly. Moseley also noticed three gaps in his table of x-ray frequencies, so he predicted the existence of three unknown elements: technetium (<em class="emphasis">Z</em> = 43), discovered in 1937; promethium (<em class="emphasis">Z</em> = 61), discovered in 1945; and rhenium (<em class="emphasis">Z</em> = 75), discovered in 1925.</p>
<div class="callout editable block" id="averill_1.0-ch07_s01_s02_n01">
<h3 class="title">H. G. J. Moseley (1887–1915)</h3>
<p class="para" id="averill_1.0-ch07_s01_s02_p02">Moseley left his research work at the University of Oxford to join the British army as a telecommunications officer during World War I. He was killed during the Battle of Gallipoli in Turkey.</p>
</div>
<div class="exercises editable block" id="averill_1.0-ch07_s01_s02_n02">
<h3 class="title">Example 1</h3>
<p class="para" id="averill_1.0-ch07_s01_s02_p03">Before its discovery in 1999, some theoreticians believed that an element with a <em class="emphasis">Z</em> of 114 existed in nature. Use Mendeleev’s reasoning to name element 114 as <em class="emphasis">eka</em>-______; then identify the known element whose chemistry you predict would be most similar to that of element 114.</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p04"><strong class="emphasis bold">Given: </strong>atomic number</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p05"><strong class="emphasis bold">Asked for: </strong>name using prefix <em class="emphasis">eka</em>-</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p06">
<strong class="emphasis bold">Strategy:</strong>
</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p07"><strong class="emphasis bold">A</strong> Using the periodic table (see <a class="xref" href="s36-appendix-h-periodic-table-of-e.html">Chapter 32 "Appendix H: Periodic Table of Elements"</a>), locate the <em class="emphasis">n</em> = 7 row. Identify the location of the unknown element with <em class="emphasis">Z</em> = 114; then identify the known element that is directly above this location.</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p08"><strong class="emphasis bold">B</strong> Name the unknown element by using the prefix <em class="emphasis">eka</em>- before the name of the known element.</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p09">
<strong class="emphasis bold">Solution:</strong>
</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p10"><strong class="emphasis bold">A</strong> The <em class="emphasis">n</em> = 7 row can be filled in by assuming the existence of elements with atomic numbers greater than 112, which is underneath mercury (Hg). Counting three boxes to the right gives element 114, which lies directly below lead (Pb). <strong class="emphasis bold">B</strong> If Mendeleev were alive today, he would call element 114 <em class="emphasis">eka</em>-lead.</p>
<p class="simpara">Exercise</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p11">Use Mendeleev’s reasoning to name element 112 as <em class="emphasis">eka</em>-______; then identify the known element whose chemistry you predict would be most similar to that of element 112.</p>
<p class="para" id="averill_1.0-ch07_s01_s02_p12"><strong class="emphasis bold">Answer: </strong><em class="emphasis">eka</em>-mercury</p>
</div>
<div class="callout editable block" id="averill_1.0-ch07_s01_s02_n03">
<h3 class="title">Summary</h3>
<p class="para" id="averill_1.0-ch07_s01_s02_p13">The periodic table arranges the elements according to their electron configurations, such that elements in the same column have the same valence electron configurations. Periodic variations in size and chemical properties are important factors in dictating the types of chemical reactions the elements undergo and the kinds of chemical compounds they form. The modern periodic table was based on empirical correlations of properties such as atomic mass; early models using limited data noted the existence of <strong class="emphasis bold">triads</strong> and <strong class="emphasis bold">octaves</strong> of elements with similar properties. The periodic table achieved its current form through the work of Dimitri Mendeleev and Julius Lothar Meyer, who both focused on the relationship between atomic mass and chemical properties. Meyer arranged the elements by their atomic volume, which today is equivalent to the <strong class="emphasis bold">molar volume</strong>, defined as molar mass divided by molar density. The correlation with the electronic structure of atoms was made when H. G. J. Moseley showed that the periodic arrangement of the elements was determined by atomic number, not atomic mass.</p>
</div>
<div class="key_takeaways editable block" id="averill_1.0-ch07_s01_s02_n04">
<h3 class="title">Key Takeaway</h3>
<ul class="itemizedlist" id="averill_1.0-ch07_s01_s02_l01">
<li>The elements in the periodic table are arranged according to their properties, and the periodic table serves as an aid in predicting chemical behavior.</li>
</ul>
</div>
<div class="qandaset block" id="averill_1.0-ch07_s01_s02_qs01" defaultlabel="number">
<h3 class="title">Conceptual Problems</h3>
<ol class="qandadiv" id="averill_1.0-ch07_s01_s02_qs01_qd01">
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs01_qd01_qa01">
<div class="question">
<p class="para">Johannes Dobereiner is credited with developing the concept of chemical triads. Which of the group 15 elements would you expect to compose a triad? Would you expect B, Al, and Ga to act as a triad? Justify your answers.</p>
</div>
</li>
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs01_qd01_qa02">
<div class="question">
<p class="para">Despite the fact that Dobereiner, Newlands, Meyer, and Mendeleev all contributed to the development of the modern periodic table, Mendeleev is credited with its origin. Why was Mendeleev’s periodic table accepted so rapidly?</p>
</div>
</li>
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs01_qd01_qa03">
<div class="question">
<p class="para">How did Moseley’s contribution to the development of the periodic table explain the location of the noble gases?</p>
</div>
</li>
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs01_qd01_qa04">
<div class="question">
<p class="para">The <em class="emphasis">eka</em>- naming scheme devised by Mendeleev was used to describe undiscovered elements.</p>
<ol class="orderedlist" numeration="loweralpha">
<li>Use this naming method to predict the atomic number of <em class="emphasis">eka</em>-mercury, <em class="emphasis">eka</em>-astatine, <em class="emphasis">eka</em>-thallium, and <em class="emphasis">eka</em>-hafnium.</li>
<li>Using the <em class="emphasis">eka</em>-prefix, identify the elements with these atomic numbers: 79, 40, 51, 117, and 121.</li>
</ol>
</div>
</li>
</ol>
</div>
<div class="qandaset block" id="averill_1.0-ch07_s01_s02_qs02" condition="1col" defaultlabel="number">
<h3 class="title">Numerical Problem</h3>
<ol class="qandadiv" id="averill_1.0-ch07_s01_s02_qs02_qd01">
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs02_qd01_qa01">
<div class="question">
<p class="para">Based on the data given, complete the table.</p>
<div class="informaltable" frame="all">
<table cellpadding="0" cellspacing="0">
<thead>
<tr>
<th align="center">Species</th>
<th align="center">Molar Mass (g/mol)</th>
<th align="center">Density (g/cm<sup class="superscript">3</sup>)</th>
<th align="center">Molar Volume (cm<sup class="superscript">3</sup>/mol)</th>
</tr>
</thead>
<tbody>
<tr>
<td>A</td>
<td align="right">40.078</td>
<td align="right"></td>
<td align="right">25.85</td>
</tr>
<tr>
<td>B</td>
<td align="right">39.09</td>
<td align="right">0.856</td>
<td align="right"></td>
</tr>
<tr>
<td>C</td>
<td align="right">32.065</td>
<td align="right"></td>
<td align="right">16.35</td>
</tr>
<tr>
<td>D</td>
<td align="right"></td>
<td align="right">1.823</td>
<td align="right">16.98</td>
</tr>
<tr>
<td>E</td>
<td align="right">26.98</td>
<td align="right"></td>
<td align="right">9.992</td>
</tr>
<tr>
<td>F</td>
<td align="right">22.98</td>
<td align="right">0.968</td>
<td align="right"></td>
</tr>
</tbody>
</table>
</div>
<p class="para">Plot molar volume versus molar mass for these substances. According to Meyer, which would be considered metals and which would be considered nonmetals?</p>
</div>
</li>
</ol>
</div>
<div class="qandaset block" id="averill_1.0-ch07_s01_s02_qs02_ans" condition="1col" defaultlabel="number">
<h3 class="title">Answer</h3>
<ol class="qandadiv">
<li class="qandaentry" id="averill_1.0-ch07_s01_s02_qs02_qd01_qa01_ans">
<div class="answer">
<div class="informaltable" frame="all">
<table cellpadding="0" cellspacing="0">
<thead>
<tr>
<th align="center">Species</th>
<th align="center">Molar Mass (g/mol)</th>
<th align="center">Density (g/cm<sup class="superscript">3</sup>)</th>
<th align="center">Molar Volume (cm<sup class="superscript">3</sup>/mol)</th>
</tr>
</thead>
<tbody>
<tr>
<td>A</td>
<td align="right">
<strong class="emphasis bold">40.078</strong>
</td>
<td align="right">1.550</td>
<td align="right">
<strong class="emphasis bold">25.85</strong>
</td>
</tr>
<tr>
<td>B</td>
<td align="right">
<strong class="emphasis bold">39.09</strong>
</td>
<td align="right">
<strong class="emphasis bold">0.856</strong>
</td>
<td align="right">45.67</td>
</tr>
<tr>
<td>C</td>
<td align="right">
<strong class="emphasis bold">32.065</strong>
</td>
<td align="right">1.961</td>
<td align="right">
<strong class="emphasis bold">16.35</strong>
</td>
</tr>
<tr>
<td>D</td>
<td align="right">30.95</td>
<td align="right">
<strong class="emphasis bold">1.823</strong>
</td>
<td align="right">
<strong class="emphasis bold">16.98</strong>
</td>
</tr>
<tr>
<td>E</td>
<td align="right">
<strong class="emphasis bold">26.98</strong>
</td>
<td align="right">2.700</td>
<td align="right">
<strong class="emphasis bold">9.992</strong>
</td>
</tr>
<tr>
<td>F</td>
<td align="right">
<strong class="emphasis bold">22.98</strong>
</td>
<td align="right">
<strong class="emphasis bold">0.968</strong>
</td>
<td align="right">23.7</td>
</tr>
</tbody>
</table>
</div>
<div class="informalfigure large medium-height">
<img src="section_11/09bbc015e35e26883500969d939bc0dc.jpg">
</div>
<p class="para">Meyer found that the alkali metals had the highest molar volumes, and that molar volumes decreased steadily with increasing atomic mass, then leveled off, and finally rose again. The elements located on the rising portion of a plot of molar volume versus molar mass were typically nonmetals. If we look at the plot of the data in the table, we can immediately identify those elements with the largest molar volumes (A, B, F) as metals located on the left side of the periodic table. The element with the smallest molar volume (E) is aluminum. The plot shows that the subsequent elements (C, D) have molar volumes that are larger than that of E, but smaller than those of A and B. Thus, C and D are most likely to be nonmetals (which is the case: C = sulfur, D = phosphorus).</p>
</div>
</li>
</ol>
</div>
</div>
</div>
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