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Chemical Bonding

Chemical Bonding. Why do bonds form?. to lower the potential energy. between positive and. negative charges. positive charges. protons. cations. negative charges. electrons. anions. non-metals. metals. gain e -. lose e -. Periodic Table. +. -. Ionic bonding. + non-metal.

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Chemical Bonding

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  1. Chemical Bonding Why do bonds form? to lower the potential energy between positive and negative charges positive charges protons cations negative charges electrons anions non-metals metals gain e- lose e- Periodic Table

  2. + - Ionic bonding + non-metal metal Groups 1 and 2 Groups 6 and 7 high Electron Affinity low Ionization Energy lose 1 or 2 valence e- gain e- electron transfer takes place electrostatic attraction between cation and anion e- formula = ratio of anions to cations

  3. Covalent bonding non-metal + non-metal electrons shared between atoms high Ionization Energies high Electron Affinities electron density between the atoms distance between atoms = bond length formula = actual # atoms

  4. Metallic Bonding metal + metal metals valence e- well shielded low Ionization Energy low Electron Affinities share valence e- not localized between atoms delocalized move freely throughout metal Na (nucleus and core e-) e- “sea” (valence e-)

  5. Ionic bonding + non-metal metal Na (s) 2  2 NaCl (s) + Cl2 (g) http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA0/Movies/NACL1.html negative exothermic heat given off Ionization Energy Na Na+ + 496 kJ/mol Electron Affinity Cl Cl- -349 kJ/mol E = -504 kJ/mol Lattice Energy k Q1 Q2 d Coulomb’s law NaCl Na+ Cl- +

  6. Lewis electron-dot symbols element symbol = nucleus + core e- one “dot” = valence e- metals dot = e- it loses to form cation non-metal e- paired through unpaired dot = e- gain or sharing

  7. Na (s) 2  2 NaCl (s) + Cl2 (g) : : : + Cl- : Ionic bonding + non-metal metal : . : . Na Na+ + Cl : [Ne] 3s1 3s23p5 [Ar] [Ne] [Ne]  2 CaO (s) + O2(g) Ca(s) 2 . . . : : Ca O . [Ar]4s2 [He]2s2 2p4 Ca2+ O2- [Ar] [Ne] Sn, Pb, Bi and Tl exceptions

  8. + - Ionic sizes e- isoelectronic series same # electrons 46 e- ions get smaller +49 +50 +51

  9. . . H H H H . . Covalent bonding non-metal + non-metal + [He] 1s1 1s1

  10. Lewis structure : : : : : . . : : : . : : F F F F F : : : : : : . . . . H H O : : . : F + : [He]2s22p5 [Ne] lone pairs e- not used in bonding shared e- bonding pair shared equally between F : . . . H O : 1s1 [He]2s22p4 [He] [Ne] oxygen 2 lone pairs bonding pair not shared equally

  11. Electronegativity in a molecule ability of an atom to attract e- to itself Ionization Energy related to Electron Affinity Pauling scale

  12. C H C O ionic > 1.8 NaCl 2.1 ionic 801oC polar covalent 405oC BeCl2 1.5 AlCl3 1.5 polar covalent 178oC PCl3 0.9 76oC polar covalent Cl2 0.0 covalent -101oC non-polar covalent 0.4 + - polar covalent0.5-1.8 Li2O

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