1 / 47

Chapter 15 Ionic Bonding and Ionic Compounds

Chapter 15 Ionic Bonding and Ionic Compounds. Milbank High School. Section 15.1 Electron Configuration in Ionic Bonding. OBJECTIVES: Use the periodic table to infer the number of valence electrons in an atom, and draw it’s electron dot structure.

southern
Download Presentation

Chapter 15 Ionic Bonding and Ionic Compounds

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 15Ionic Bonding and Ionic Compounds Milbank High School

  2. Section 15.1Electron Configuration in Ionic Bonding • OBJECTIVES: • Use the periodic table to infer the number of valence electrons in an atom, and draw it’s electron dot structure.

  3. Section 15.1Electron Configuration in Ionic Bonding • OBJECTIVES: • Describe the formation of cations from metals, and of anions from nonmetals.

  4. Valence Electrons • The electrons responsible for the chemical properties of atoms are those in the outer energy level. • Valence electrons - The s and p electrons in the outer energy level • the highest occupied energy level • Core electrons -those in the energy levels below.

  5. Keeping Track of Electrons • Atoms in the same column... • Have the same outer electron configuration. • Have the same valence electrons. • Easily found: group number on the periodic table for representative elem. • Group 2A: Be, Mg, Ca, etc. • 2 valence electrons

  6. Electron Dot diagrams • Write the symbol. • Put one dot for each valence electron • Don’t pair up until they have to (Hund’s rule) 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 electron dot diagrams: • Na • Mg • C • O • F • Ne • V

  9. Electron Configurations for Cations • Metals lose electrons to attain noble gas configuration. • They make positive ions (cations) • If we look at the electron configuration, it makes sense to lose electrons: • Na 1s22s22p63s1 1 valence electron • Na1+1s22s22p6 noble gas configuration

  10. Electron Dots For Cations • Metals will have few valence electrons (usually 3 or less) Ca

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

  12. Electron Dots For Cations • Metals will have few valence electrons • These will come off • Forming positive ions Ca2+

  13. Electron Configurations for Anions • Nonmetals gain electrons to attain noble gas configuration. • They make negative ions (anions) • Halide ions- ions from chlorine or other halogens that gain electrons • S 1s22s22p63s23p4 6 valence electrons • S2-1s22s22p63s23p6 noble gas configuration.

  14. Electron Dots For Anions • Nonmetals will have many valence electrons (usually 5 or more) • They will gain electrons to fill outer shell. P P3-

  15. Stable Electron Configurations • All atoms react to achieve noble gas configuration. • Noble gases have 2 s and 6 p electrons. • 8 valence electrons . • Also called the octet rule. Ar

  16. Section 15.2Ionic Bonds • OBJECTIVES: • List the characteristics of an ionic bond.

  17. Section 15.2Ionic Bonds • OBJECTIVES: • Use the characteristics of ionic compounds to explain the electrical conductivity of ionic compounds when melted and when in aqueous solution.

  18. Ionic Bonding • Anions and cations are held together by opposite charges. • Ionic compounds are called salts. • Simplest ratio is called the formula unit. • The bond is formed through the transfer of electrons. • Electrons are transferred to achieve noble gas configuration.

  19. Ionic Bonding Na Cl

  20. Ionic Bonding Na+ Cl-

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

  22. Ionic Bonding Ca P

  23. Ionic Bonding Ca2+ P

  24. Ionic Bonding Ca2+ P Ca

  25. Ionic Bonding Ca2+ P 3- Ca

  26. Ionic Bonding Ca2+ P 3- Ca P

  27. Ionic Bonding Ca2+ P 3- Ca2+ P

  28. Ionic Bonding Ca Ca2+ P 3- Ca2+ P

  29. Ionic Bonding Ca Ca2+ P 3- Ca2+ P

  30. Ionic Bonding Ca2+ Ca2+ P 3- Ca2+ P 3-

  31. Ionic Bonding = Ca3P2 Formula Unit Sample Problem 15-1, page 421

  32. Properties of Ionic Compounds • Crystalline structure, usually solids • A regular repeating arrangement of ions in the solid: Fig. 15.9, p.423 • Ions are strongly bonded together. • Structure is rigid. • High melting points • Coordination number- number of ions of opposite charge surrounding it

  33. 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. • NaCl: must get to about 800 ºC. • Dissolved in water they conduct (aqueous)

  34. Section 15.3Bonding in Metals • OBJECTIVES: • Use the theory of metallic bonds to explain the physical properties of metals.

  35. Section 15.3Bonding in Metals • OBJECTIVES: • Describe the arrangements of atoms in some common metallic crystal structures.

  36. Metallic Bonds • How atoms are held together in the solid. • Metals hold on to their valence electrons very weakly. • Think of them as positive ions (cations) floating in a sea of electrons: Fig. 15.13, p.427

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

  38. Metals are Malleable • Hammered into shape (bend). • Also ductile - drawn into wires. • Both malleability and ductility explained in terms of the mobility of the valence electrons • Fig. 15.14, p.427

  39. + + + + + + + + + + + + Malleable

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

  41. + - + - - + - + + - + - - + - + Ionic solids are brittle

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

  43. Crystalline structure of metal • If made of one kind of atom, metals are among the simplest crystals • Note Fig. 15.16, p.428 for types: 1. Body-centered cubic: • every atom has 8 neighbors • Na, K, Fe, Cr, W

  44. Crystalline structure of metal 2. Face-centered cubic: • every atom has 12 neighbors • Cu, Ag, Au, Al, Pb 3. Hexagonal close-packed • every atom also has 12 neighbors • different pattern due to hexagonal • Mg, Zn, Cd

  45. Alloys • Alloys - mixtures of 2 or more elements, at least 1 is a metal • Brass: an alloy of Cu and Zn • Bronze: Cu and Sn

  46. Why use alloys? • Sterling silver (92.5% Ag, 7.5% Cu) is harder and more durable than pure Ag, but still soft enough to make jewelry and tableware • Steels are very important alloys • corrosion resistant, ductility, hardness, toughness, cost

  47. Why use alloys? • Table 15.3, p.429 - common alloys • Types? a) substitutional alloy- the atoms in the components are about the same size • b) interstitial alloy- the atomic sizes quite different; smaller atoms fit into the spaces between larger • Amalgam- dental use, contains Hg

More Related