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CHEMISTRY 161 Chapter 9 Chemical Bonding I chem.hawaii/Bil301/welcome.html

CHEMISTRY 161 Chapter 9 Chemical Bonding I www.chem.hawaii.edu/Bil301/welcome.html. Periodic Table of the Elements. ns 2 np 6. ns 1. ns 2. chemical reactivity - valence electrons. THE OCTET RULE. atoms combine to form compounds in an attempt to obtain a stable

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CHEMISTRY 161 Chapter 9 Chemical Bonding I chem.hawaii/Bil301/welcome.html

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  1. CHEMISTRY 161 Chapter 9 Chemical Bonding I www.chem.hawaii.edu/Bil301/welcome.html

  2. Periodic Table of the Elements ns2np6 ns1 ns2 chemical reactivity - valence electrons

  3. THE OCTET RULE atoms combine to form compounds in an attempt to obtain a stable noble gas electron configuration ns2np6 isoelectronic

  4. A + B → AB 1. ELECTRON FULLY TRANSFERED IONIC BONDING NaCl 2. ELECTRON SHARING COVALENT BONDING HCl

  5. LEWIS MODEL OF BONDING LEWIS DOT SYMBOL DOT represents one valence electron H. Gilbert Lewis (1875-1946)

  6. . . . . . . . . . . with the exception of He, the main group number represents number of ‘dots’

  7. IONIC BONDING Na electron transfer Ne core implied in symbol 1s22s22p63s1 Lewis Symbol

  8. Na Ne core implied in symbol Cl 1s22s22p63s23p5 1s22s22p63s1 Lewis Symbol

  9. IONIC BONDING Cl Cl Na the formation of ionic bonds is represented in terms of Lewis symbols  Na+ 1s22s22p63s23p6 1s22s22p6 the loss or gain of electrons(dots) until both species have reached an octet of electrons

  10. Cl Cl [Ne] 3s23p6 represents one orbital (Pauli: 2 electrons)

  11. ions stack together in regular crystalline structures electrostatic interaction ionic solids typically 1. high melting and boiling points 2. brittle 3. form electrolyte solutions if they dissolve in water

  12. Li(s) + ½ F2(g) → LiF(s) enthalpy of formation lattice energy Li+(g) + F-(g) → LiF(s) Hess’s Law enthalpy is a state function Born-Haber Cycle

  13. Li(s) + ½ F2(g) → LiF(s) Li+(g) + F-(g) 5 ΔHoR= ΣΔHoi i=1 ΔHo4 ΔHo3 ΔHo5 Li(g) + F(g) ΔHo2 ΔHo1 ΔHoR LiF(s) Li(s) + ½ F2(g)

  14. Mg(s) + ½ O2(g) → MgO(s) Mg2+(g) + O2-(g) ΔHo6 7 ΔHo5 ΔHoR= ΣΔHoi i=1 Mg+(g) + O-(g) ΔHo7 ΔHo4 ΔHo3 Mg(g) + O(g) ΔHo1 ΔHo2 ΔHoR MgO(s) Mg(s) + ½ O2(g)

  15. SUMMARY Lewis Dot Octett Rule Lattice Energy of Ionic Compounds 600 – 4000 kJmol-1

  16. Homework Chapter 9 pages 329-337, problem sets

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