文档介绍：【王鑫托福阅读】托福TPO 16-2阅读文本
TPO 16
　　TPO16-2 Development of the Periodic Table
　　1. The phrase interplay in the passage is closest in meaning to
　　A. sequence
　　B. interpretation
　　C. requirement
　　D. interaction
　　2. According to paragraph 1, what pattern did scientists notice when the known elements were written in order of increasing atomic mass? elements of the group of alkali metals were the first elements in the order of increasing atomic mass.
　　B. Repetition of the same atomic masses for elements in different groups appeared.
　　C. Elements with similar chemical properties appeared in the listing at regular intervals.
　　D. Elements were chemically most similar to those just before and after them in the order.
　　%
　　v
　　The periodic table is a chart that reflects the periodic recurrence of chemical and physical properties of the elements when the elements are arranged in order of increasing atomic number (the number of protons in the nucleus). It is a monumental scientific achievement, and its development illustrates the essential interplay between observation, prediction, and testing required for scientific progress. In the 1800's scientists were searching for new elements. By the late 1860's more than 60 chemical elements had been identified, and much was known about their descriptive chemistry. Various proposals were put forth to arrange the elements