General features in properties of p-block elements The properties of p-block elements show secondary periodic trends when descending in the same groups. 1The p-block elements in the 2ed row (i.e.,B,C,N,O,F) are abnormal in many ways compared to the other elements of the corresponding groups (only having 2s,2p orbits) Example:1)形成配合物时，配位数最多不超过4；2)第二 周期元素单键键能小于第三周期元素单键键能。 EN-N)=159E(0-0)=142EF-F)=158 EP-P)=209E(S-S)=264 E(C1-CI)=244 N,O,F原子半径小，成键时N-N,O-O,F-F键长短，未参与成键 的电子间排斥作用大，削弱了共价键的强度) ① The p-block elements in the 2ed row (i.e., B, C, N, O, F) are abnormal in many ways compared to the other elements of the corresponding groups (only having 2s, 2p orbits) Example: 1)形成配合物时，配位数最多不超过4；2)第二 周期元素单键键能小于第三周期元素单键键能. General features in properties of p-block elements ‹ The properties of p-block elements show secondary periodic trends when descending in the same groups. E(N-N)=159 E(O-O)=142 E(F-F)=158 E(P-P)=209 E(S-S)=264 E(Cl-Cl)=244 (N,O,F原子半径小, 成键时N-N, O-O, F-F键长短, 未参与成键 的电子间排斥作用大, 削弱了共价键的强度)