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Chapter 7

Chapter 7 . Ionic and Metallic Bonding. Ionic and Metallic Bonding. Ionic Bond:  bond between 2 oppositely charged ions Cation (+) & Anion (-) Metal & Nonmetal Metal & Polyatomic ion Properties of Ionic Bonds:

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Chapter 7

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  1. Chapter 7 Ionic and Metallic Bonding

  2. Ionic and Metallic Bonding • Ionic Bond: •  bond between 2 oppositely charged ions Cation (+) & Anion (-) Metal & Nonmetal Metal & Polyatomic ion • Properties of Ionic Bonds: •  Involve transfer of electron between metal and nonmetal •  Very Strong • Form “salts” or Group I hydroxides •  only 1 force (forces/bonds between + to – ions the same)

  3. Ionic Compound: • Compounds made up of (+) and (-) ions • Ex; Na + Cl  Na+Cl- • Na (Ne)3s1 Cl (Ne)3s23p5 • - • + Called a “formula unit” • Properties of Ionic Compounds: • crystalline solids at room temperature • High melting points (indicates strength of bonds) • tend to dissolve in water • conduct electricity in “molten” and aqueous state Cl Na

  4. Look at the reaction of Na + Cl to make NaCl: (3 step process that occurs simultaneously) 1. Na + ionization energy  Na+ + 1e-(endothermic) • Cl + 1e-  Cl-1 + electron affinity energy (exothermic) • Na+ + Cl-  NaCl + lattice energy (exothermic) Net result is Exothermic

  5. Lattice Energy: •  energy released when oppositely charged ions bond to form a crystal lattice or solid salt • Compounds form to get lowest possible energy • Atoms react to achieve noble gas configuration (stable octet) • For atoms that attract, when they come together ENERGY is ____________ • therefore energy is ________to pull them apart. • Bonds Forming _________energy. • Bonds Breaking ________energy. released required give off exothermic absorb endothermic

  6. Crystal Structure of Ionic Compounds: Strong IONIC BOND holding the + and - together. Regular repeating pattern (lattice) Crystal Arrangement: __________________________ Glue between the ions in an ionic compound is ___________________________ Valence electrons: ____________________________ Coordination Number: ___________________________ Shape of the crystal depends on ___________________ NaCl is ________________________________ An electrostatic attraction between the + and – ions e- involved in bonding (highest occupied shell) # of + charged ions surrounding - ions size and arrangement of ions cubic and its coordination # is 6

  7. oppositely charged ions nonmetals lowest whole # ratio of ions OR atoms • Ionic Compounds: Composed of _____________________________ • Molecular Compounds: Composed of _______________ • Empirical Formula: __________________________________ • Molecular Formula: __________________________________ • Ionic compounds do not have “molecular formulas” because they are not composed of molecules which have a unique association between atoms. • Bothionic and molecular compounds have __________________ • Onlymolecular compounds have __________________________ • For molecular compounds, their empirical and molecular formulas may be ________________ ratio of atoms in a molecule of a compound. How it actually exists. EMPERICAL FORMULAS MOLECULAR FORMULAS THE SAME

  8. Determine if the compound is Ionic or Molecular and if it is and Empirical Formula, Molecular Formula or Both YES YES YES YES YES YES YES YES YES YES YES YES YES CH2O YES YES YES YES

  9. Compare SALT Crystal to ICE Crystal: Distinct Units Intermolecular Forces between 2 adjacent water molecules Intramolecular Forces make water ICE: Molecular Compound: Contains TWO forces. Melting Point is comparatively low compared to salt because breaking weaker intermolecular bond between 2 different water mc’s, not strong covalent bond between 0-H that makes water. No Distinct Units • SALT: Ionic Compound: • Contains ONE force. • Melting Point is high because • only one strong ionic bond must be broken (400°C)

  10. 2 Forces of Molecular Compounds • 1. Intramolecular force: • 2. Intermolecular force: Strong covalent bonds WITHIN water molecules. (Holds H & O atoms together) MAKES WATER MC. Weak bonds BETWEEN different water molecules. The slightly – oxygen end of one water mc is attracted to the slightly + end of a nearby water mc.

  11. + + + + + + + + + + + + Metallic Bonds and Metallic Properties • Metals are made up of ________________________ (positive ions) rather than neutral atoms. • The valence electrons of metal atoms can be thought of as a sea of electrons. closely packed CATIONS

  12. Metallic Bonds • Attraction of free floating valence electrons for the + charged metal ions. • Crystalline Structure of Metals • Metal atoms are arranged in very _______________________________________  • Especially since they are all the same size. compact and orderly patterns.

  13. Alloys 2 or more elements. • are mixture composed of ___________________ • (at least one must be a metal) • Ex. Brass is a physical blend of _______________ • Steel is a blend of ___________________ copper & zinc. iron and carbon

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