University:
Boston University
Course:
CAS CH 101 | General Chemistry 1
Academic year:

2022
Views:

461

Pages:

1
Author:

Nikolas Jacobson

Class Handout on Multi-electron atoms 1. (a) Larger nuclear charge (𝑍) = larger effective nuclear charge (𝑍! ) ⟶ that means higher ionization energy (b) More loops = larger 𝑛 ⟶ so ionization energy decreases (c) This would shield the electron. Shielding causes the electron wave to increase in energy, and so the ionization energy decreases (d) Electron-electron repulsion tends to decrease the ionization energy. 2. Ionization energy: 𝐼 = Δ𝐸 = 𝐸" − 𝐸# = 𝐸$ − 𝐸% = 0 + ('.)* ,-)/!" %" = ('.)* ,-)0" # %" Atom Z Electron configuration Trend in ionization energy compared to previous atom, and explanation H 1 1s1 He 2 1s2 IE of He is higher than H, because He has a larger nuclear charge, but the electron being ionized is still n = 1 (increased effective nuclear charge) Li 3 1s22s1 IE of Li is lower than He, because the electron ionized from He is 1s and the electron ionized from Li is 2s (new shell) Be 4 1s22s2 IE of Be > IE of Li, because of the increased effective nuclear charge. B 5 1s22s2 2px1 C 6 1s22s2 2px1 2py1 IE of C > IE of B, because of the increased effective nuclear charge N 7 1s22s2 2px1 2py1 2pz1 IE of N > IE of C, because of the increased effective nuclear charge O 8 1s22s2 2px1 2py2 2pz1 IE of O < IE of N, because pairing a 2p electron causes a large increase in electron/electron repulsion (increased electron/electron repulsion) F 9 1s22s2 2px2 2py2 2pz1 IE of F > IE of O, because of the increased effective nuclear charge Ne 10 1s22s2 2p6 IE of Ne > IE of F, because of the increased effective nuclear charge Na 11 1s22s2 2p6 3s1 IE of Na < IE of Ne, because the Na valence electron is part of a new shell. Mg 12 1s22s2 2p6 3s2 IE of Mg > IE of Na, because of the increased effective nuclear charge. Al 13 1s22s2 2p6 3s2 3py1 Si 14 1s22s2 2p6 3s2 3py13pz1 P 15 … – IE of B < IE of Be, because 2p is more shielded than 2s. So the 2p orbital energy is higher ⟶ so the IE of a 2p electron is lower (more shielding) IE of Al < IE of Mg, because of more shielding IE of Si > IE of Al, because of the increased effective nuclear charge …