Similarity of elements in periods 5 and 6镧系收缩:s-La to zLu ， the radius of Lu isonly 0.11A°less than that of LaLanthanide contraction causes the radii ofelements of period 6 almost equal to thoseof elements in the same group of period 5
6 Similarity of elements in periods 5 and 6 镧系收缩:57La to 71Lu ，the radius of Lu is only 0.11Aºless than that of La Lanthanide contraction causes the radii of elements of period 6 almost equal to those of elements in the same group of period 5
中间排异样性Elements in period 4 having 3d10Compared with elements in periods 2 and 3the effective nuclear charge (Z*) increaseand the radius decrease, which causebiggerZ*/rvalueand biggerelectronegativityvalue
7 中间排异样性 Elements in period 4 having 3d10 Compared with elements in periods 2 and 3, the effective nuclear charge (Z*) increase and the radius decrease，which cause bigger Z*/r value and bigger electronegativity value
2 Halogens2-1 General properties2-2 Elements2-2-1 Properties2-2-2 Preparations (制备)2-2-3 Usages2-3 Compounds2-3-1 HX2-3-2 HalidesInterhalogencompounds（卤素间化合物）Polyhalogen compounds(多卤化物)2-3-3 Oxides (OF2, CIO2, I,Os)2-3-4Oxiacids（含氧酸）/salts
8 2 Halogens 2-1 General properties 2-2 Elements 2-2-1 Properties 2-2-2 Preparations (制备) 2-2-3 Usages 2-3 Compounds 2-3-1 HX 2-3-2 Halides Interhalogen compounds (卤素间化合物) Polyhalogen compounds(多卤化物) 2-3-3 Oxides (OF2 , ClO2 , I2O5 ) 2-3-4 Oxiacids (含氧酸) /salts
2-1 General propertiesOuter electron configuration: ns?np5Oxidation numbersionic bond, NaFcovalent bond, HFcoordination bond, BF4、 AgCl+1， +3， +5， +7when halogen element combine with moreelectronegative elements, such as CiO andpolyhalogen compounds
9 2-1 General properties ◼ Outer electron configuration：ns2np5 ◼ Oxidation numbers -1 ionic bond, NaF covalent bond, HF coordination bond, BF4 －、AgCl2 － +1，+3，+5，+7 when halogen element combine with more electronegative elements, such as ClO2 and polyhalogen compounds
Existing form in nature: X-, MXFrom F to I, r increase,while I、 E,、 XdecreaseWith an exception: Eic> EiF10
10 ◼ Existing form in nature：X－, MXn ◼ From F to I, r increase， while I1、E1、X decrease With an exception：E1Cl > E1F