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UNIT 2

UNIT 2. Atoms, Ions, Electronic Structure, and Periodic Properties of Atoms and Ions. Electronic Models of the Atom. Bohr Model 1. Initial model. These ideas got things started. 2. Classical physics does not apply in the atom.

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UNIT 2

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  1. UNIT 2 Atoms, Ions, Electronic Structure, and Periodic Properties of Atoms and Ions

  2. Electronic Models of the Atom Bohr Model 1. Initial model. These ideas got things started. 2. Classical physics does not apply in the atom. 3. Electrons orbit the nucleus, but only orbits of certain energies (designated by n) are allowed. Quantum-Mechanical Model 1. Currently accepted model. xxx 2. Classical physics does not apply in the atom. 3. Electrons occupy orbitals designated by n, l, ml. ms gives the spin of the electron in the orbital.

  3. Electronic Models of the Atom Quantum-Mechanical Model 4. Same as Bohr #4, but change “orbit” to “orbital.” 5. The behavior of the electron in the atom is governed by probabilities, not certainties. Bohr Model 4. Electrons can change from one allowed orbit to another, but that the change will either require energy or produce energy. The energy involved is often in the form of light.

  4. Light is Energy: E = hυ • Energy can • cause electrons to move to a higher energy orbital. • cause chemical bonds to break.

  5. Light Can Break Chemical Bonds The C-C bond has an energy of 368 kJ/mol. What wavelength of light will break one (1) C-C bond? 368 kJ x 1 mol C-C bonds x 1000J mol C-C bonds 6.022 x 1023 C-C bonds 1kJ = 6.111 x 10-19 J per C-C bond This gives the energy needed to break the bond, so now this must be converted to a wavelength…

  6. Light Can Break Chemical Bonds The C-C bond has an energy of 368 kJ/mol. What wavelength of light will break one (1) C-C bond? E = 6.111 x 10-19 J per C-C bond E = hv E = hc/λ c = λv or λ = hc/E λ = (6.626 x 10-34 J-s)(3.00 x 108 m/s) = 3.25 x 10-7 m 6.111 x 10-19 J λ = 325 nm (visible light?)

  7. Valence Electrons • Chemistry happens among valence electrons because generally they are the outermost electrons. • Valence electrons are usually the electrons in the s and p orbitals of the highest energy shell.

  8. Electron Configurations of the Elements Atomic # Element # of e- in e- configuration (Z) 1s 2s 2p 3s 3p 4s full core _________ ________ ________________ ___________________ 1 H 1 1s1 2 He 2 1s2 [He] 3 Li 2 1 1s22s1 [He]2s1 4 Be 2 2 1s22s2 [He]2s2 5 B 2 2 1 1s22s22p1 [He]2s22p1 6 C 2 2 2 1s22s22p2 [He]2s22p2 7 N 2 2 3 1s22s22p3 [He]2s22p3 8 O 2 2 4 1s22s22p4 [He]2s22p4 9 F 2 2 5 1s22s22p5 [He]2s22p5 10 Ne 2 2 6 1s22s22p6 [Ne] Chemistry happens amongvalence electrons. Hund’s rule: Electrons in a degenerate subshell (such as a p, d or f subshell) will fill the orbitals in such a way as to maximize the number of unpaired electrons. Inert gas electronic configurations are VERY stable.

  9. Electron Configurations of the Elements Atomic # Element # of e- in e- configuration (Z) 3s 3p 4s 3d full core _________ ________ __________ __________________________ 11 Na 1 1s22s22p63s1 [Ne]3s1 12 Mg 2 1s22s22p63s2 [Ne]3s2 13 Al 2 1 1s22s22p63s23p1 [Ne]3s23p1 14 Si 2 2 1s22s22p63s23p2 [Ne]3s23p2 15 P 2 3 1s22s22p63s23p3 [Ne]3s23p3 16 S 2 4 1s22s22p63s23p4 [Ne]3s23p4 17 Cl 2 5 1s22s22p63s23p5 [Ne]3s23p5 18 Ar 2 6 1s22s22p63s23p6 [Ar] Element electron n l ml ms _________ ________ ___ ____ _____ _____ S 1st 3p 3 1 -1 +1/2 S 2nd 3p 3 1 0 +1/2 S 3rd 3p 3 1 +1 +1/2 S 4th 3p 3 1 -1 -1/2 Cl 1st 3p 3 1 -1 +1/2* *The Pauli Exclusion Principle says that no two electrons in an atom may have the same four quantum numbers. Cl is a different atom.

  10. Orbital Energy Diagram 6p 5d 4f 6s 5p 4d 5s 4p 3d 4s ENERGY 3p 3s 2p 2s Energy spacing between orbitals becomes smaller with higher n, allowing electrons to fill and/or move between adjacent subshells with relative ease. 1s

  11. Electron Configurations of the Elements Atomic # # of e- in e- configuration (Z) / Element 3s 3p 3d 4s 4p full core notation ___________ ____________ ________________________________ 19 K 2 6 1 1s22s22p63s23p64s1 [Ar]4s1 20 Ca 2 6 2 1s22s22p63s23p64s2 [Ar]4s2 21 Sc 2 6 1 2 1s22s22p63s23p63d14s2 [Ar]3d14s2 22 Ti 2 6 2 2 1s22s22p63s23p63d24s2 [Ar]3d24s2 23 V 2 6 3 2 1s22s22p63s23p63d34s2 [Ar]3d34s2 24 Cr 2 6 5 1 1s22s22p63s23p63d54s1 [Ar]3d54s1 25 Mn 2 6 5 2 1s22s22p63s23p63d54s2 [Ar]3d54s2 26 Fe 2 6 6 2 1s22s22p63s23p63d64s2 [Ar]3d64s2 27 Co 2 6 7 2 1s22s22p63s23p63d74s2 [Ar]3d74s2 28 Ni 2 6 8 2 1s22s22p63s23p63d84s2 [Ar]3d84s2 29 Cu 2 6 10 1 1s22s22p63s23p63d104s1 [Ar]3d104s1 30 Zn 2 6 10 2 1s22s22p63s23p63d104s2 [Ar]3d104s2 31 Ga 2 6 10 2 1 1s22s22p63s23p63d104s24p1 [Ar]3d104s24p1 32 Ge 2 6 10 2 2 1s22s22p63s23p63d104s24p2 [Ar]3d104s24p2 33 As 2 6 10 2 3 1s22s22p63s23p63d104s24p3 [Ar]3d104s24p3 34 Se 2 6 10 2 4 1s22s22p63s23p63d104s24p4 [Ar]3d104s24p4 35 Br 2 6 10 2 5 1s22s22p63s23p63d104s24p5 [Ar]3d104s24p5 36 Kr 2 6 10 2 6 1s22s22p63s23p63d104s24p6 [Kr] half-filled and filled subshells are energetically favored

  12. Electron Configurations of the Elements Atomic # e- configuration (Z) / Element full core notation ___________ _____________________________________________________ 55 Cs 1s22s22p63s23p63d104s24p64d105s25p66s1 [Xe]6s1 56 Ba 1s22s22p63s23p63d104s24p64d105s25p66s2 [Xe]6s2 57 La 1s22s22p63s23p63d104s24p64d105s25p65d16s2 [Xe]5d16s2 58 Ce 1s22s22p63s23p63d104s24p64d105s25p64f15d16s2 [Xe]4f15d16s2 59 Pr 1s22s22p63s23p63d104s24p64d105s25p64f36s2 [Xe]4f36s2 60 Nd 1s22s22p63s23p63d104s24p64d105s25p64f46s2 [Xe]4f46s2 79 Au 1s22s22p63s23p63d104s24p64d105s25p64f145d106s1 [Xe]4f145d106s1 83 Bi 1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p3 [Xe]4f145d106s26p3

  13. How to Find the Electronic Configuration of an Ion • Find the electronic configuration of the parent atom. • Add or remove electrons from that configuration to form the ion: • (+) charge (cation): remove e-’s • Be sure to remove the electrons from the orbital with the highest principle quantum number n. • (-) charge (anion): add e-’s

  14. Electron Configurations of Ions Z Element e- configuration ion e- configuration _____ _______ ________________ _____ _______________ 1 H 1s1 H+ no electrons H- 1s2 3 Li [He]2s1Li+ [He] 4 Be [He]2s2Be2+ [He] 5 B [He]2s22p1B3+ [He] 6 C [He]2s22p2C4- [Ne] 7 N [He]2s22p3N3- [Ne] 8 O [He]2s22p4O2- [Ne] 9 F [He]2s22p5F- [Ne] Lose electrons to get an inert gas configuration. Gain electrons to get an inert gas configuration.

  15. Electron Configurations of Ions Z Element e- configuration ion e- configuration __ ________ ________________ _____ _______________ 19 K [Ar]4s1K+ [Ar] 20 Ca [Ar]4s2Ca2+ [Ar] 22 Ti [Ar]3d24s2 Ti2+, Ti4+[Ar]3d2, [Ar] 24 Cr [Ar]3d54s1Cr3+, Cr6+[Ar]3d3, [Ar] 26 Fe [Ar]3d64s2Fe2+, Fe3+[Ar]3d6, [Ar]3d5 29 Cu [Ar]3d104s1 Cu+, Cu2+[Ar]3d10, [Ar]3d9 30 Zn [Ar]3d104s2 Zn2+ [Ar]3d10 31 Ga [Ar]3d104s24p1Ga3+ [Ar]3d10 35 Br [Ar]3d104s24p5 Br- [Kr] half-filled and filled subshells are energetically favored

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