L8_Chap4英文版原子物理课件.ppt

4 The alkalis 4.1 Shell structure and the periodic table_1 4.1 Shell structure and the periodic table_2 4.1 Shell structure and the periodic table_3 4.1 Shell structure and the periodic table_4 4.2 The quantum defect_1 4.2 The quantum defect_2 4.2 The quantum defect_3 4.2 The quantum defect_5 4.2 The quantum defect_6 4.3 The central-field approximation_1 4.3 The central-field approximation_2 4.3 The central-field approximation_3 4.3 The central-field approximation_4 4.3 The central-field approximation_5 4.3 The central-field approximation_6 4.3 The central-field approximation_7 4.3 The central-field approximation_8 4.3 The central-field approximation_1 4.3 The central-field approximation_9 4.3 The central-field approximation_10 4.3 The central-field approximation_11 4.3 The central-field approximation_12 2-1 2-2 2-2 * *Shanxi University Atomic Physics The ‘building-up’ principle: electrons fill up higher and higher shells as the atomic number Z increases across the periodic table. Full shells are found at atomic number Z=2,10,…corresponding to helium and the other inert gases. These inert gases were originally grouped together because of their similar chemical properties, i.e. the difficulty in removing an electron from closed shells means that they do not readily undergo chemical reactions. However, inert gas atoms can be excited to higher-lying configurations by bombardment with electrons in a gas discharge, and such processes are very important in atomic and laser physics, as in the helium-neon laser. Each alkali metal comes next to an inert gas in the periodic table and much of the chemistry of the alkali can be explained by the simple picture of their atoms as having a single unpaired electron outside a core of closed electronic sub-shells surrounding the nucleus. The unpaired valence electron determines the chemical bonding properties; since it takes less energy to remove this outer electron than to pull an electron out of a closed sub-shell (see Table 4.1