Irma

托福分類單字 "Chemistry" 化學 (一)

化學這個主題我覺得是托福聽力比較偏愛的題材，尤其是托福聽力的講座考題類型中常出現，但托福閱讀我覺得就自己做過的題目中算是非常少相關的。而且化學這個部分就算在外國新聞上相關資料我覺得也偏少，化學類的單字又非常多的專有名詞，算是不是很好背的單字類型，所以在準備托福時化學絕對不可以忽略但也不用查找太深入的相關知識新聞內容，基本的單字一定要把握不然萬一考出來真的會很慘。

　1)  元素 element

　2)　族group

　3)　物理性質physical property

　4)　化學性質chemical property

　5)　同位素isotope

　6)　原子序數atomic number

　7)　原子atom

　8)　原子核nucleus

　9)　質子proton

　10) 中子neutron

　11) 電子electron

   12) 質子proton

   13) 分子molecule  

　14) 粒子 particle

　15) 離子 ion

  截取托福閱讀文章(化學類)：

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 relative abundance 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.