Bonding(1) (1) - Models of Chemical Bonding 3 ways that metals and nonmetals combine The three bonds Electronegativity Scale Difference in

Bonding(1) (1) - Models of Chemical Bonding 3 ways that...

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Models of Chemical Bonding 3 ways that metals and nonmetals combine
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The three bonds
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Electronegativity Scale Difference in electronegativity is one way to determine type of bond
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Electronegativity Difference and Bond Type If the difference in electronegativity between bonded atoms is 0, the bond is pure covalent . Equal sharing If the difference in electronegativity between bonded atoms is 0.1 to 0.4, the bond is nonpolar covalent . If the difference in electronegativity between bonded atoms is 0.5 to 1.9, the bond is polar covalent . If difference in electronegativity between bonded atoms is larger than or equal to 2.0, the bond is ionic .
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Ionic Bond An ionic bond forms from electrostatic attraction of ions. Usually it is between a metal and a nonmetal or a metal and a polyatomic ion.
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Lattice Energy A quantitative measurement of the stability of any ionic solid is its lattice energy Can also be used to compare bond strengths in ionic compounds. chemists compare the amounts of energy released when separated ions in a gas come together to form a crystalline solid. Yup – another enthalpy H lattice
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Lattice Energy Trends: As you move up in a column, lattice energy increases: - higher up, higher lattice energy Li + Na + K + Rb + Cs + F - 1036 923 821 785 740 Cl - 853 787 715 689 659 Br - 807 747 682 660 631 I - 757 704 649 630 604 The force of attraction between oppositely charged particles is directly proportional to the product of the charges on the two objects ( q 1 and q 2 ) and inversely proportional to the square of the distance between the objects ( r 2 ). Lattice energy increases as Q increases and/or as r decreases . Moving up a column = smaller ionic radii
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Lattice Energy versus Ion Size
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Lattice Energy Trends: As you increase the magnitude of the charge (becomes more positive or more negative), lattice energy increases Na + Mg 2+ Al 3+ OH - 900 3006 5627 O 2- 2481 3791 15916 Lattice energy increases as Q increases and/or as r decreases . Higher charge = higher q
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Trends in Lattice Energy: Ion Charge The force of attraction between oppositely charged particles is directly proportional to the product of the charges. Larger charge means the ions are more strongly attracted. Larger charge = stronger attraction Stronger attraction = larger lattice energy Of the two factors, ion charge is generally more important.
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13 Born-Haber Cycle for Determining Lattice Energy H overall = H 1 + H 2 + H 3 + H 4 + H 5 o o o o o o Uses Hess’ Law: Also known as heat of formation You will get to do this in a cool powerpoint for part of the Lewis Quiz
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Metallic Bonding Metallic Compounds Are a crystal made out of just metals – like an iron nail or a clump of aluminum In a metallic bond the electrons are delocalized – which means they do not belong to any one specific atom, but are free to move about the metal crystal.
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