4 Quantum Numbers (n, l, ml, ms) principal quantum number energy level of the orbital (1, 2, 3, 4,… # e- = 2n2) n 1 2 3 4 5 6 7

Pauli Exclusion Principle No two electrons in an atom can have the same four quantum numbers. Wolfgang Pauli

Electron Configurations Distribution of all electrons in an atom Consist of Number for the energy level (n) 4 p 5 1s2 2s2 2p4 1s2 2s2 2p4

Electron Configurations Distribution of all electrons in an atom Consist of Number for the energy level (n) Letter for the shape of orbital (s,p,d,f) 4 p 5 1s2 2s2 2p4 1s2 2s2 2p4

Electron Configurations Distribution of all electrons in an atom. Consist of Number for the energy level (n). Letter for the shape of orbital (s,p,d,f). Superscript for the number of electrons in those orbitals. 4 p 5 1s2 2s2 2p4 1s2 2s2 2p4

Electron Configurations Write the e-con or symbol of the element Element Electron Config. Noble Gas Core Na 1s22s22p6 3s1 [Ne] 3s1 Al 1s22s22p6 3s23p1 [Ne] 3s23p1 Cl 1s22s22p6 3s23p5 [Ne] 3s23p5 Valence e-s Valence e-s Identify the valence electrons in your notes.

Orbital Diagrams Li Each box represents one orbital. Half-arrows represent the electrons. The direction of the arrow represents the spin of the electron. 3 Li 6.94 1s 2s 2p Pauli exclusion principle: no 2 e- can have same 4 #’s (must have opp. spin, ↑↓)

Aufbau Principle Fill orbitals of lower energy first.

Hund’s Rule “For degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximized.” 7 N 14.0 1s 2s 2p if more than one orbital of the same energy, then one e– is placed into each orbital before any pairing takes place

Noble gas Li 1s22s1 [He]2s1 Be 1s22s2 [He]2s2 B 1s22s22p1 [He]2s22p1 C Element Configuration Orbital notation Noble gas Li 1s22s1 ____ ____ ____ ____ ____ 1s 2s 2p [He]2s1 Be 1s22s2 [He]2s2 B 1s22s22p1 [He]2s22p1 C 1s22s22p2 [He]2s22p2 N 1s22s22p3 [He]2s22p3 O 1s22s22p4 [He]2s22p4 F 1s22s22p5 [He]2s22p5 Ne 1s22s22p6 [Ne]

Electron Configuration Micro-Tutorial Energy 2 1 1 2 1 6 3 2 4 5 1 2 6 3 2 1 5 4 1 2 2 1 3 6 7 8 9 5 4 10 3 4 6 1 5 2 1s 2s 2p 3s 3p 4s 3d 4p 2s 2p 1s 3s 3p 4s 4p 3d H He Li Be Be C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Exceptions A half-filled or completely filled d shell is more stable than an s. So instead of the EXPECTED… An s electron is promoted to the d shell to create a more stable configuration. At Z=24, Cr… 1s2 2s2 2p6 3s2 3p6 4s2 3d4 At Z=29, Cu…1s2 2s2 2p6 3s2 3p6 4s2 3d9 1s2 2s2 2p6 3s2 3p6 4s1 3d5 1s2 2s2 2p6 3s2 3p6 4s1 3d10

Exceptions At Z=___,Mo 42 [Kr] 5s1 4d5 At Z=___, Ag 47 [Kr] 5s1 4d10 Molybdenum and Silver are similar exceptions… Note their juxtaposition on the periodic table.

IONS Ions – Lose or gain e- to mimic noble gas (i) F- (ii) Ca2+ (iii) S2- (iv) Na+ (v) Al3+ Ion Configuration Noble Gas Core Electron Configuration 1s2 2s2 2p6 [Ne] 1s2 2s2 2p6 3s2 3p6 [Ar] 1s2 2s2 2p6 3s2 3p6 [Ar] 1s2 2s2 2p6 [Ne] 1s2 2s2 2p5 1s2 2s2 2p6 3s2 3p6 4s2 1s2 2s2 2p6 3s2 3p4 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 3p1

Other Aspects Paramagnetic species are those that are attracted by a magnet (caused by unpaired electrons in an unfilled subshell) i.e., Fe: [Ar] ↑↓ ↑↓ ↑ ↑ ↑ ↑ 4s 3d Diamagnetic species are slightly repelled by magnets (caused by all electrons in subshell being paired) i.e., Be: [He] ↑↓ 2s

Other Aspects Fe 1s2 2s2 2p6 3s2 3p6 3d6 4s2 d block metals lose their outer s electrons before any d electrons to form ions. Fe 1s2 2s2 2p6 3s2 3p6 3d6 +2 4s2

Other Aspects d block metals lose their outer s electrons before any core d electrons to form ions. Fe 1s2 2s2 2p6 3s2 3p6 4s2 3d6 Fe2+ 1s2 2s2 2p6 3s2 3p6 3d6 Fe3+ 1s2 2s2 2p6 3s2 3p6 3d5 d block (trans. metals) have colored ions due to light excited e– movement in d orbitals

Other Aspects Isoelectronic species have the same electronic configuration. (Na+, Ne, F-) Therefore, they must be distinguished by the number of protons present.

Other Aspects Which ions are isoelectronic? Ions (i) F- 1s2 2s2 2p6 [Ne] (ii) Ca2+ 1s2 2s2 2p6 3s2 3p6 [Ar] (iii) S2- 1s2 2s2 2p6 3s2 3p6 [Ar] (iv) Na+ 1s2 2s2 2p6 [Ne] (v) Al3+ 1s2 2s2 2p6 [Ne]