Electron Configuration Electrons in Atoms Electron Configuration

General Rules Pauli Exclusion Principle Each orbital can hold TWO electrons with opposite spins.

General Rules Aufbau Principle Electrons fill the lowest energy orbitals first. “Lazy Tenant Rule” Energy levels overlap Expected order: 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f... Actual order: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f...

General Rules WRONG RIGHT Hund’s Rule Within a sublevel, place one e- per orbital before pairing them. “Empty Bus Seat Rule” WRONG RIGHT

S 16e- 1s2 2s2 2p6 3s2 3p4 S 16e- [Ne] 3s2 3p4 Orbital Notation Longhand Configuration S 16e- 1s2 2s2 2p6 3s2 3p4 Core Electrons Valence Electrons Shorthand Configuration S 16e- [Ne] 3s2 3p4

Orbital Notation Shows the arrangement of electrons in orbitals within a sublevel. Use squares to represent orbitals. Arrow up represents 1 electron. Arrow up and arrow down represents 2 electrons.

1s2 2s2 2p4 O Orbital Notation 1s 2s 2p 8e- Orbital Diagram Electron Configuration 1s2 2s2 2p4

Orbital Diagrams for Nickel 58.6934 28 2 2 6 2 6 2 8 1s 2s 2p 3s 3p 4s 3d 2s 2p 3s 3p 4s 3d 1s Excited State 2 2 6 2 6 1 9 2s 2p 3s 3p 4s 3d 1s Pauli Exclusion 2s 2p 3s 3p 4s 3d 1s Hund’s Rule

Periodic Patterns s p d (n-1) f (n-2) 1 2 3 4 5 6 7 6 7 © 1998 by Harcourt Brace & Company

Electron Filling in Periodic Table s s s s H 1s1 He 1s2 H 1s1 p p 1 1 Li 2s1 Be 2s2 B 2p1 C 2p2 N 2p3 O 2p4 F 2p5 Ne 2p6 2 2 Na 3s1 Mg 3s2 d d Al 3p1 Si 3p2 P 3p3 S 3p4 Cl 3p5 Ar 3p6 3 3 K 4s1 Ca 4s2 Sc 3d1 Ti 3d2 V 3d3 Cr 3d5 Mn 3d5 Fe 3d6 Co 3d7 Ni 3d8 Cu 3d10 Zn 3d10 Ga 4p1 Ge 4p2 As 4p3 Se 4p4 Br 4p5 Kr 4p6 4 4 Rb 5s1 Sr 5s2 Y 4d1 Zr 4d2 Nb 4d4 Mo 4d5 Tc 4d6 Ru 4d7 Rh 4d8 Pd 4d10 Ag 4d10 Cd 4p1 In 5p1 Sn 5p2 Sb 5p3 Te 5p4 I 5p5 Xe 5p6 5 5 Cs 6s1 Ba 6s2 Hf 5d2 Ta 5d3 W 5d4 Re 5d5 Os 5d6 Ir 5d7 Pt 5d9 Au 5d10 Hg 5d10 Tl 6p1 Pb 6p2 Bi 6p3 Po 6p4 At 6p5 Rn 6p6 6 6 * * Fr 7s1 Ra 7s2 Rf 6d2 Db 6d3 Sg 6d4 Bh 6d5 Hs 6d6 Mt 6d7 7 7 W W f f La 5d1 Ce 4f2 Pr 4f3 Nd 4f4 Pm 4f5 Sm 4f6 Eu 4f7 Gd 4f7 Tb 4f9 Dy 4f10 Ho 4f11 Er 4f12 Tm 4f13 Yb 4f14 Lu 4f114 * * Ac 6d1 Th 6d2 Pa 5f2 U 5f3 Np 5f4 Pu 5f6 Am 5f7 Cm 5f7 Bk 5f8 Cf 5f10 Es 5f11 Fm 5f14 Md 5f13 No 5f14 Lr 5f14 W W

Periodic Patterns Period # energy level (subtract for d & f) A/B Group # total # of valence e- Column within sublevel block # of e- in sublevel

1s1 Periodic Patterns 1st column of s-block 1st Period s-block Example - Hydrogen 1s1 1st column of s-block 1st Period s-block

Periodic Patterns p s d (n-1) f (n-2) Shorthand Configuration Core e-: Go up one row and over to the Noble Gas. Valence e-: On the next row, fill in the # of e- in each sublevel. s d (n-1) f (n-2) p

Periodic Patterns Example - Germanium [Ar] 4s2 3d10 4p2

Stability Full energy level Full sublevel (s, p, d, f) Half-full sublevel

Stability (Honors Only) Electron Configuration Exceptions Copper EXPECT: [Ar] 4s2 3d9 ACTUALLY: [Ar] 4s1 3d10 Copper gains stability with a full d-sublevel.

Stability (Honors Only) Electron Configuration Exceptions Chromium EXPECT: [Ar] 4s2 3d4 ACTUALLY: [Ar] 4s1 3d5 Chromium gains stability with a half-full d-sublevel.

Stability 1+ 3+ NA 3- 2- 1- 2+ Ion Formation Atoms gain or lose electrons to become more stable. Isoelectronic with the Noble Gases. (No charge) 1+ 3+ NA 3- 2- 1- 2+

O2- 10e- [He] 2s2 2p6 Stability Ion Electron Configuration Write the e- config for the closest Noble Gas EX: Oxygen ion  O2-  Ne O2- 10e- [He] 2s2 2p6