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Ionic and Metallic Bonding

Ionic and Metallic Bonding. Chapter 7. Valence Electrons. The electrons in the highest occupied energy level Number of valence electrons is related to the group number. Valence Electrons. Electron Dot Structures. Diagrams that show valence electrons as dots. The Octet Rule.

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Ionic and Metallic Bonding

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  1. Ionic and Metallic Bonding Chapter 7

  2. Valence Electrons • The electrons in the highest occupied energy level • Number of valence electrons is related to the group number

  3. Valence Electrons

  4. Electron Dot Structures • Diagrams that show valence electrons as dots

  5. The Octet Rule • In forming compounds atoms tend to achieve the electron configuration of a noble gas

  6. The Octet Rule • Atoms of metals tend to lose electrons • This leaves a full octet in the next lowest energy level • Atoms of nonmetals tend to gain electrons or share

  7. Formation of Cations • If an atom loses an e- it becomes positively charged

  8. Formation of Anions • If an atom gains an e- it becomes negatively charged

  9. Common Anions

  10. Assessment • p 193 7.1 #1-10

  11. Formation of Ionic Compounds • Compounds composed of cations and anions are called ionic compounds

  12. Formation of Ionic Compounds • Although they are composed of ions, compounds are neutral • The total positive charge of the cations equals the total negative charge of the anions

  13. Ionic Bonds • Anions and cations attract each other • The electrostatic forces that hold ions together are known as ionic bonds

  14. Ionic Bonds

  15. Ionic Bonds

  16. Chemical Formula • A chemical formula shows the kinds and numbers of atoms in the smallest representative unit of a substance

  17. Formula Units • The lowest whole number ratio of ions in an ionic compound 1:1 ratio

  18. Formula Unit • A magnesium ion has a charge of +2 • A chloride ion has a charge of -1 • What is the formula unit?

  19. Formula Unit • Magnesium has a charge of +2 • Nitrogen has a charge of -3 • What is the formula unit?

  20. 7.2 Assessment • p. 196 12-13

  21. Properties of Ionic Compounds • Most ionic bonds are crystalline structures at room temperature • Composition of crystals is very structured

  22. Properties of Ionic Bonds • Ionic Bonds generally have high melting points • Solutions of ions can conduct an electric current

  23. Electrode

  24. Coordination Number • The number of ions of opposite charge that surrounds an ion in a crystal Na+ - 6 Cl- - 6

  25. Coordination Number • Aluminum is +3 • Iodide is -1 • What is the formula unit?

  26. Coordination Number

  27. 7.2 Assessment • p 199 #14-22

  28. Metallic Bonds • Metals are made up of closely packed cations rather than a neutral ion • Metal atoms tend to share valence e- • Sea of e-

  29. Metallic Bonds • Metallic bonds consist of the attraction of the free-floating e- to the positively charge metal ions • These bonds hold metal together • Ductile • Maliable

  30. Crystalline Structure of Metals • Metal atoms are arranged in very compact and orderly patterns • Many different patterns are found • p. 202

  31. Alloys • Most metals you encounter are alloys • Alloys are mixtures composed of two or more elements

  32. Alloys • Properties of alloys are usually superior to properties of original elements • What are some common alloys?

  33. Alloys • If atoms are similar in size they can replace each other • Substitutional alloy

  34. Alloys • If atoms are different sizes the smaller on can fit into the spaces (interstices) • Interstitial alloy • Carbon fits between iron atoms forming steel

  35. 7.3 Assessment • p. 203 #23-27, 29

  36. Chapter 7 Assessment • pp. 207-208 #30-33, 35-37, 41-45, 48, 50

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