问一道题，TPO16 第二篇第6题

sasha_wen · 发表于 2011-11-28 00:24:03

Paragraph 2: When the German chemist Lothar Meyer and (independently) the Russian Dmitry Mendeleyev first introduced the periodic table in 1869-70, one-third of the naturally occurring chemical elements had not yet been discovered. Yet both chemists were sufficiently farsighted to leave gaps where their analyses of periodic physical and chemical properties indicated that new elements should be located. Mendeleyev was bolder than Meyer and even assumed that if a measured atomic mass put an element in the wrong place in the table, the atomic mass was wrong. In some cases this was true. Indium, for example, had previously been assigned an atomic mass between those of arsenic and selenium. Because there is no space in the periodic table between these two elements, Mendeleyev suggested that the atomic mass of indium be changed to a completely different value, where it would fill an empty space between cadmium and tin. In fact, subsequent work has shown that in a periodic table, elements should not be ordered strictly by atomic mass. For example, tellurium comes before iodine in the periodic table, even though its atomic mass is slightly greater. Such anomalies are due to the relativeabundance of the "isotopes" or varieties of each element. All the isotopes of a given element have the same number of protons, but differ in their number of neutrons, and hence in their atomic mass. The isotopes of a given element have the same chemical properties but slightly different physical properties. We now know that atomic number (the number of protons in the nucleus), not atomic mass number (the number of protons and neutrons), determines chemical behavior.

6. It can be inferred from paragraph 2 that tellurium comes before iodine in the periodic table even though tellurium's atomic mass is slightly greater because

○iodine is less common than tellurium

○both iodine and tellurium have no isotopes

○the chemical behavior of tellurium is highly variable

○the atomic number of tellurium is smaller than that of iodine

为什么是D

sasha_wen · 发表于 2011-11-30 23:48:54

luoalbert · 发表于 2012-1-30 14:44:12

AB文章没有提到，C答案不能解释，因为文章指提到了Such anomalies are due to the relative abundance of the "isotopes" or varieties of each element。而答案C指的是 chemical behavior is variable。
D选项正好符合题意，题目是推断题，原文Such anomalies are due to the relativeabundance of the "isotopes" or varieties of each element. All the isotopes of a given element have the same number of protons, but differ in their number of neutrons, and hence in their atomic mass.支持了D选项

问一道题，TPO16 第二篇第6题

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