【环境地质学】地球物质的化学组成.pptVIP

环境地质学Environmental Geology 主讲人：万新南教授 　　　　Prof. Wan xinnan 4、地球物质的化学组成　Rock and Minerals in earth  4、地球物质的化学组成　Rock and Minerals in earth  4、地球物质的化学组成　Rock and Minerals in earth  4、地球物质的化学组成　Rock and Minerals in earth  4、地球物质的化学组成　Rock and Minerals in earth  4、地球物质的化学组成　Rock and Minerals in earth  环境地质学 Environmental Geology * Atomic Structure All natural and most synthetic substances on earth are made from the ninety naturally occurring chemical elements. An atom is the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element (fig 3.1). The nucleus, at the center of the atom, contains one or more particles with a positive electrical charge (protons质子) and usually some particles of similar mass that have no charge (neutrons中子). Circling the nucleus核 are the negatively charged electrons. Elements and Isotopes 4. With the exception of the simplest hydrogen atoms, all nuclei contain neutrons, and the number of neutrons is similar to or somewhat greater than the number of protons. The number of neutrons in atoms of one element is not always the same. The sum of the number of protons and the number of neutrons in a nucleus is the atoms atomic mass number. Atoms of a given element with different atomic mass numbers—in other words, with the same number of protons but different numbers of neutrons—are distinct isotopes of that element. Some elements have only a single isotope, while others may have ten or more. (The Chemical Symbols 8. Each chemical element is denoted by a one-or two-letter symbol. Many of these symbols make sense in terms of the English name for the element--O for oxygen, He for helium, Si for silicon, and so on. Other symbols reflect the fact that, in earlier centuries, scientists were generally versed in Latin or Greek: The symbols Fe for iron and Pb for lead, for example, and derived from ferrum and plumbum, respectively, the Latin names for these elements. Minerals D