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Ionic Bonding

Ionic Bonding. Keeping Track of Electrons. The electrons that are responsible for the chemical properties of atoms are those in the outer energy level. Valence electrons - The outer electrons. Core electrons -those in the inside. Keeping Track of Electrons.

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Ionic Bonding

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  1. Ionic Bonding

  2. Keeping Track of Electrons • The electrons that are responsible for the chemical properties of atoms are those in the outer energy level. • Valence electrons - The outer electrons. • Core electrons -those in the inside.

  3. Keeping Track of Electrons • Same column = same valence electrons. • Easily found by looking up the group number on the periodic table. • Group 2A - Be, Mg, Ca, etc.- • 2 valence electrons

  4. Electron Dot diagrams • A way of keeping track of valence electrons. • How to write them • Write the symbol. • Put one dot for each valence electron • Don’t pair up until they have to X

  5. The Electron Dot diagram for Nitrogen • Nitrogen has 5 valence electrons. • First we write the symbol. N • Then add 1 electron at a time to each side. • Until they are forced to pair up.

  6. Write the electron dot diagram for • Na • Mg • C • O • F • Ne • He

  7. Electron Configurations for Cations • Metals lose electrons to attain noble gas configuration. • They make positive ions.

  8. Electron Dots For Cations • Metals lose electrons to look like noble gases. • They make positive ions. • Metals will have few valence electrons Ca

  9. Electron Dots For Cations • Metals will have few valence electrons • These will come off Ca

  10. Electron Dots For Cations • Metals will have few valence electrons • These will come off • Forming positive ions Ca+2

  11. Electron Configurations for Anions • Nonmetals gain electrons to look like noble gases. • They make negative ions.

  12. Electron Dots For Anions • Nonmetals will have many valence electrons. • They will gain electrons to fill outer shell. P P-3

  13. Stable Outer Shells • All atoms react to look like noble gases. • 8 valence electrons . • Also called the octet rule. Ar

  14. Ionic Bonding • Anions and cations are held together by the attraction between opposite charges. • Ionic compounds are called “salts”. • The simplest ratio is called the formula unit. • The bond is formed through the transfer of electrons.

  15. Ionic Bonding Na Cl

  16. Ionic Bonding Na+ Cl-

  17. Ionic Bonding • All the electrons must be accounted for! Ca P

  18. Ionic Bonding Ca P

  19. Ionic Bonding Ca+2 P

  20. Ionic Bonding Ca+2 P Ca

  21. Ionic Bonding Ca+2 P-3 Ca

  22. Ionic Bonding Ca+2 P-3 Ca P

  23. Ionic Bonding Ca+2 P-3 Ca+2 P

  24. Ionic Bonding Ca Ca+2 P-3 Ca+2 P

  25. Ionic Bonding Ca Ca+2 P-3 Ca+2 P

  26. Ionic Bonding Ca+2 Ca+2 P-3 Ca+2 P-3

  27. Ionic Bonding Ca3P2 Formula Unit

  28. Properties of Ionic Compounds • Crystalline structure. • A regular repeating arrangement of ions in the solid. • Ions are strongly bonded. • Structure is rigid. • High melting points- because of strong forces between ions.

  29. Crystalline structure

  30. Do they Conduct? • Conducting electricity is allowing charges to move. • In a solid, the ions are locked in place. • Ionic solids are insulators. • When melted, the ions can move around. • Melted ionic compounds conduct. • First get them to 800ºC. • Dissolved in water they conduct.

  31. Metallic Bonds • How atoms are held together in the solid. • Metals hold onto their valence electrons very weakly. • Think of them as positive ions floating in a sea of electrons.

  32. + + + + + + + + + + + + Sea of Electrons • Electrons are free to move through the solid. • Metals conduct electricity.

  33. Metals are Malleable • Hammered into shape (bend). • Ductile - drawn into wires.

  34. + + + + + + + + + + + + Malleable

  35. + + + + + + + + + + + + Malleable • Electrons allow atoms to slide by.

  36. + - + - - + - + + - + - - + - + Ionic solids are brittle

  37. - + - + - + - + + - + - - + - + Ionic solids are brittle • Strong Repulsion breaks crystal apart.

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