PF1009 2024 4 Electronic Configuration of Atoms PDF

Pharmaceutical Chemistry Electronic Configuration of Atoms Dr. J.J. Keating 1  Electronic Configuration of Atoms Number of electrons in each main energy level = electronic configuration. Element Z...

Pharmaceutical Chemistry Electronic Configuration of Atoms Dr. J.J. Keating 1  Electronic Configuration of Atoms Number of electrons in each main energy level = electronic configuration. Element Z Electrons in each shell Electron configuration n=1 n=2 n=3 n=4 H 1 1 1 He 2 2 2 Li 3 2 1 2,1 Be 4 2 2 2,2 Ne 10 2 8 2,8 Na 11 2 8 1 2,8,1 Ar 18 2 8 8 2,8,8 K 19 2 8 8 1 2,8,8,1 2  Electronic Configuration of Atoms Shell, sublevel, orbitals, electrons s-sublevel 2 e– (1 orbital) p-sublevel (px, py, pz) 6 e– (3 orbitals) d-sublevel 10 e– (5 orbitals) f-sublevel 14 e– (7 orbitals) Aufbau (building up) Principle When building up the electronic configuration of an atom in its ground state, the electrons occupy the lowest available energy state. Valence shell Outermost shell. Valence electrons Electrons that occupy the valence shell. 3  Electronic Configuration of Atoms Since the 4s sublevel is lower in energy than the 3d sublevel, the 4s sublevel is always filled before the 3d sublevel. Element Z Electronic Configuration H 1 1s1 Na 11 1s2, 2s2, 2p6, 3s1 Sc 21 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d1 V 23 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d3 Cr 24 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5 Ni 28 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d8 Cu 29 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d10 Zn 30 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10 Nd 60 [Xe] 4f4, 6s2 Pb 82 [Xe] 4f14, 5d10, 6s2, 6p3 Hund’s rule of maximum multiplicity – When two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs. 4  Electronic Configuration of Atoms Pauli Exclusion Principle – No more than two electrons may occupy an orbital and they must have opposite spin. 5B 1s2, 2s2, 2px1, 2py0, 2pz0 6C 1s2, 2s2, 2px1, 2py1, 2pz0 7N 1s2, 2s2, 2px1, 2py1, 2pz1 8O 1s2, 2s2, 2px2, 2py1, 2pz1 9F 1s2, 2s2, 2px2, 2py2, 2pz1 10Ne 1s2, 2s2, 2px2, 2py2, 2pz2 Configuration of ions Cations – If the principal quantum number of the valence shell is n, remove electrons in the order np, ns, (n – 1)d Fe = [Ar]3d64s2 Fe3+ = [Ar]3d5 Anions – monoatomic anions are formed by adding enough electrons to the vacant orbitals of the valence shell to achieve the configuration of the next noble gas atom. N = [He]2s2, 2px1, 2py1, 2pz1 5 N3– (azide) = [He]2s2, 2px2, 2py2, 2pz2