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Quantum Model of the Atom. Electron Configuration & Orbitals. Ch. 4 - Electrons in Atoms. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 …. Quantum Model of the Atom. Ch. 4 - Electrons in Atoms.
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Quantum Model of the Atom Electron Configuration & Orbitals Ch. 4 - Electrons in Atoms 1s22s22p63s23p64s23d104p65s24d104p65s24d105p66s24f145d106p6…
Quantum Model of the Atom Ch. 4 - Electrons in Atoms Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electrons as Waves • Louis de Broglie (1924) • Applied wave-particle theory to electrons • electrons exhibit wave properties Louis de Broglie ~1924 QUANTIZED WAVELENGTHS Standing Wave Fundamental mode Second Harmonic or First Overtone 200 150 100 50 0 - 50 -100 -150 -200 200 150 100 50 0 - 50 -100 -150 -200 200 150 100 50 0 - 50 -100 -150 -200 0 50 100 150 200 0 50 100 150 200 0 50 100 150 200 Adapted from work by Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electrons as Waves QUANTIZED WAVELENGTHS Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
VISIBLE LIGHT ELECTRONS Electrons as Waves Evidence: DIFFRACTION PATTERNS Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Davis, Frey, Sarquis, Sarquis, Modern Chemistry2006, page 105
Quantum Mechanics • Heisenberg Uncertainty Principle • Impossible to know both the velocity and position of an electron at the same time Werner Heisenberg ~1926 g Microscope Electron
Quantum Mechanics • SchrödingerWave Equation(1926) • finite # of solutions quantized energy levels • defines probability of finding an electron Erwin Schrodinger ~1926 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Orbital Quantum Mechanics • Orbital (“electron cloud”) • Region in space where there is 90% probability of finding an electron 90% probability of finding the electron Electron Probability vs. Distance 40 30 20 Electron Probability (%) 10 0 0 50 100 150 200 250 Distance from the Nucleus (pm) Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
UPPER LEVEL Quantum Numbers • Four Quantum Numbers: • Specify the “address” of each electron in an atom Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers Principal Quantum Number( n) Angular Momentum Quantum #( l) Magnetic Quantum Number( ml) Spin Quantum Number( ms)
Relative Sizes 1s and 2s 1s 2s Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 334
Quantum Numbers 1. Principal Quantum Number( n) • Energy level • Size of the orbital • n2 = # of orbitals in the energy level 1s 2s 3s Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers y y y z z z x x x px pz py
p-Orbitals px pz py Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 335
s p d f Quantum Numbers 2. Angular Momentum Quantum #( l) • Energy sublevel • Shape of the orbital Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
2s 2px 2py 2pz Quantum Numbers • Orbitals combine to form a spherical shape. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers n = 1 n = 2 n = 3 Principal level s p s s p d Sublevel dx2- y2 px py px py dxz dyz dz2 dxy pz pz Orbital • n = # of sublevels per level • n2 = # of orbitals per level • Sublevel sets: 1 s, 3 p, 5 d, 7 f Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Maximum Capacities of Subshells and Principal Shells n 1 2 3 4 ...n l 0 0 1 0 1 2 0 1 2 3 Subshell designation s s p s p d s p d f Orbitals in subshell 1 1 3 1 3 5 1 3 5 7 Subshell capacity 2 2 6 2 6 10 2 6 10 14 Principal shell capacity 2 8 18 32 ...2n2 Hill, Petrucci, General Chemistry An Integrated Approach1999, page 320
Quantum Numbers 3. Magnetic Quantum Number( ml) • Orientation of orbital • Specifies the exact orbital within each sublevel Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
d-orbitals Zumdahl, Zumdahl, DeCoste, World of Chemistry2002, page 336
s, p, and d-orbitals B p orbitals: Each of 3 pairs of lobes holds 2 electrons = 6 electrons (outer orbitals of Groups 13 to 18) C d orbitals: Each of 5 sets of lobes holds 2 electrons = 10 electrons (found in elements with atomic no. of 21 and higher) A s orbitals: Hold 2 electrons (outer orbitals of Groups 1 and 2) Kelter, Carr, Scott, , Chemistry: A World of Choices1999, page 82
Quantum Numbers 4. Spin Quantum Number( ms) • Electron spin +½ or -½ • An orbital can hold 2 electrons that spin in opposite directions. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Quantum Numbers • Pauli Exclusion Principle • No two electrons in an atom can have the same 4 quantum numbers. • Each electron has a unique “address”: • 1. Principal # • 2. Ang. Mom. # • 3. Magnetic # • 4. Spin # • energy level • sublevel (s,p,d,f) • orbital • electron Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Feeling overwhelmed? Read Section 4-2! Chemistry "Teacher, may I be excused? My brain is full." Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Electron Orbitals: Electron orbitals Equivalent Electron shells (a) 1s orbital (b) 2s and 2p orbitals c) Neon Ne-10: 1s, 2s and 2p 1999, Addison, Wesley, Longman, Inc.
O O H H O H H O H H O H H C H H O H H O H H H H What sort of covalent bonds are seen here? (b)O2 (a)H2 (c)H2O (d)CH4