2.屏蔽效应(续) (1)3d电子能量: 2sc原子的电子排布: (1s(2s2p9)(323p0)(3d)(4s2) 3d=1×18=18.0 Z3=Z-a3=21-18.0=30 nE3d=-(z3d2/m2)×136 -(3.02/32)×136=-136eV 7.eV 对2Sc:E3n<E4s2. 屏蔽效应（续） （1）3d 电子能量: ◼ 21Sc原子的电子排布: (1s 2 )(2s 22p 6 ) (3s 23p 6 ) (3d 1 )(4s 2 ) 3d= 1×18= 18.0 Z3d ﹡ = Z - 3d = 21 - 18.0 = 3.0 ◼ E3d = - (Z3d ﹡2 / n 2 ) ×13.6 = - (3.02 / 32 ) × 13.6 = -13.6 eV < E4s = -7.7 eV. ◼ 对21Sc ：E3d < E4s