Arranging the four Cl atoms around the P atom,connecting them with single bonds and completing the octets on the Cl atoms uses all 32 electrons.The molecule is thus of the form AX,and must be tetrahedral. (ii)[5 marks]PCls 5+(5 x 7)+1=41 electrons Arranging the five Cl atoms around the Patom,connecting them with single bonds and completing the octets on the Cl atoms uses 40 electrons.The last electron goes on the P atom as a single electron.The molecule is thus of the form AXsE and must be square pyramidal (b)[10 marks]How much energy (in kJ mol)is required to ionize H atoms whose electrons are initially in the m=2 shell?The Rydberg constant,R,is0.01097nm 品剖 In this case,the electron is beginning at m=2 and being removed from the atom,i.e.n=. Thus, 是R安剖 =0.25R =0.25(0.01097nm-) =0.00274nm- 1 1=0.0274nm-365nm E=hu-he 6.63×1034Js(3.00×10°ms) 365×10-m =5.45x10-1J(perphoton) ×6.02×1023mor1=3.28×105Jmo =32.8kJmol- Arranging the four Cl atoms around the P atom, connecting them with single bonds and completing the octets on the Cl atoms uses all 32 electrons. The molecule is thus of the form AX4 and must be tetrahedral. (ii) [5 marks] PCl5 – 5 + (5 x 7) + 1 = 41 electrons Arranging the five Cl atoms around the P atom, connecting them with single bonds and completing the octets on the Cl atoms uses 40 electrons. The last electron goes on the P atom as a single electron. The molecule is thus of the form AX5E and must be square pyramidal. (b) [10 marks] How much energy (in kJ mol-1) is required to ionize H atoms whose electrons are initially in the m = 2 shell? The Rydberg constant, R, is 0.01097 nm-1. 2 2 1 11 R m n ⎛ ⎞ = − ⎜ ⎟ λ ⎝ ⎠ In this case, the electron is beginning at m = 2 and being removed from the atom, i.e. n = ∞. Thus, 2 2 1 1 1 34 8 1 9 19 23 1 5 1 1 1 11 R 2 0.25R 0.25(0.01097nm ) 0.00274nm 1 365nm 0.00274nm hc E h 6.63 10 Js(3.00 10 ms ) 365 10 m 5.45 10 J(per photon) 6.02 10 mol 3.28 10 Jmol 32.8kJmol − − − − − − − − − − ⎛ ⎞ = − ⎜ ⎟ λ ∞ ⎝ ⎠ = = = λ = = = υ= λ × × = × = × ×× = × =