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Chapter 8

Chapter 8. Ionic Bonding. Question of the Day. Question: Write the electron level configurations for the Noble gases. He Ar Kr Xe. I. Chemical Bonds. A. The force that holds two atoms together. 1. Why do atoms form bonds? a. to acquire 8 electrons in the

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Chapter 8

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  1. Chapter 8 Ionic Bonding

  2. Question of the Day • Question: Write the electron level configurations for the Noble gases. He Ar Kr Xe

  3. I. Chemical Bonds • A. The force that holds two atoms together. 1. Why do atoms form bonds? a. to acquire 8 electrons in the valence shell (like noble gases 2. How do atoms form bonds? a. atoms may lose, gain or share electrons to get 8 in the valence shell

  4. A. Chemical Bond and valence electron 1.The electrons responsible for the chemical properties of atoms are those in the outer energy level: VALENCE ELECTRONS. a.Valence electrons - The electrons in the outer energy level. b.Inner electrons -those in the energy levels below.

  5. Keeping Track of Electrons 2. Atoms in the same column a. Have the same outer electron configuration. b. Have the same valence electrons. c. Easily found by looking up the group number on the periodic table. d. Group 2A - Be, Mg, Ca, etc.- 2 valence electrons

  6. B. Electron Dot Diagrams: Lewis Structures 1. A way of keeping track of valence electrons. 2. How to write them 3. Write the symbol. 4. Put one dot for each valence electron 5. Don’t pair up until they have to X

  7. 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.

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

  9. C. Ion Formation in Representative Elements Group Gain or Lose Charge of Ion 1 (1A) lose 1 +1 2 (2A) lose 2 +2 13 (3A) lose 3 +3 14 (4A) lose or gain 4* +4,-4* 15 (5A) gain 3 -3 16 (6A) gain 2 -2 17 (7A) gain 1 -1

  10. C. Electron Configurations for Cations 1. Metals lose electrons to attain noble gas configuration. 2. They make positive ions. 3. If we look at electron configuration it makes sense. • Na 1s22s22p63s1: 1 valence electron • Na+ 1s22s22p6 :noble gas configuration

  11. Electron Dots For Cations • Metals will have few valence electrons Ca

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

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

  14. Write the electron configuration diagram label as anion or cation • Na • Mg • P • O • F • Cl • K

  15. D. Electron Configurations for Anions 1. Nonmetals gain electrons to attain noble gas configuration. 2. They make negative ions. 3. If we look at electron configuration it makes sense. • S 1s22s22p63s23p4: 6 valence electrons • S-2 1s22s22p63s23p6:noble gas configuration.

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

  17. E. Stable Electron Configuration 1.All atoms react to achieve noble gas configuration. 2.Noble gases have 2 s and 6 p electrons. 3. 8 valence electrons . 4. Also called the octet rule. Ar

  18. I. Properties of Ionic Compounds View Ionic video a. Crystalline structure. b. A regular repeating arrangement of ions in the solid. c. Structure is rigid.

  19. II. Ionic Bonding A. Anions and cations are held together by opposite charges. B. Ionic compounds are called salts. C. Simplest ratio is called the formula unit. D.The bond is formed through the transfer of electrons. E. Electrons are transferred to achieve noble gas configuration.

  20. Formation and Nature of Ionic Bonds F. 1. atom “M” loses electron(s)  cation 2. atom “N” gains electron(s)  anion 3. cation and anion attract each other a. electrostatic attraction 4. the electrostatic force that holds the oppositely charged ions together is the ionic bond

  21. Sodium loses an electron forming a (+) ion. Chlorine gains an electron forming a ( - ) ion. Electrostatic attraction between the (-) and (+) ion forms the ionic bond between sodium and chlorine

  22. B. Ionic Compounds 1. compounds containing ionic bonds 2. types of ionic compounds a. oxides– metal + oxygen Na2O, CaO, Al2O3, Fe2O3 b. salt – metal + nonmetal NaCl CaF AgCl KI c. binary compounds – two elements 1)all of the compounds in a and b are binary compounds

  23. D. monoatomicion - one atom 1) ex. K+ Fe3+ O2- N3- E. polyatomic ion – ion with more than one atom that acts as a single ion NO3- OH- SO42- NH4+

  24. Work on ion formation and the periodic table worksheet. • Complete notes sheet

  25. III. Names and Formulas • Formulas for Ionic Compounds 1. vocabulary a. formula unit – simplest ratio of ions in a compound 1) ex. NaCl MgBr2 AlCl3 b.monoatomicion - one atom 1) ex. K+ Fe3+ O2- N3- c. oxidation number – charge of the monoatomic ion 1) ex. K is +1 O is -2 N is -3

  26. d. polyatomic ion – ion with more than one atom that acts as a single ion NO3- OH- SO42- NH4+ 2. composition of ionic compounds a. metal + nonmetal (NaCl) b. metal + polyatomic ion(MgSO4) c. polyatomic ion + nonmetal (NH4Cl) d. polyatomic ion + polyatomic ion NH4NO3

  27. B. Formulas For Ionic Compounds 1. write formula for the cation first, then the anion 2. use subscripts to indicate number of ions (criss-cross the charges) a. sum of charges should equal 0 b. never change subscripts in polyatomic ions c. put polyatomic ions in parentheses when there is more than one

  28. Sodium Chloride Crystal

  29. Ionic Bonding Na Cl

  30. Ionic Bonding: Lewis Structure Na+ Cl -

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

  32. Ionic Bonding Ca P

  33. Ionic Bonding Ca+2 P

  34. Ionic Bonding Ca+2 P Ca

  35. Ionic Bonding Ca+2 P-3 Ca

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

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

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

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

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

  41. Ionic Bonding Ca3P2 Formula Unit

  42. Shortcut • Ca+2 P-3 • Ca3P2 • Crisscross the charges to become the subscript!!!!!!!!!!!!!!!!!!!!!!!!!

  43. quiz

  44. I. Properties of Ionic Compounds a. Crystalline structure. b. A regular repeating arrangement of ions in the solid. c. Structure is rigid.

  45. Crystalline structure

  46. NaCl: Ionic Compounds Ionic compounds consist of a lattice of positive and negative ions. Lattice: three dimensional array of ions

  47. Crystalline Structure • 1. forms a lattice crystal- a 3-d geometric structure. a. each negative ion is surrounded by positive ions. b. Lattice energy- the energy required to break one mole of ions from the ionic bond the more energy – the harder it is to break-pg 220

  48. Ionic properties d. Ions are strongly bonded- because of strong forces between ions they have 1. High melting points 2. high boiling point 3. high hardness scale 4. very rigid 5. very brittle

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