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Chapter 7

Chapter 7. Ionic and Metallic Bonding. Bonding--definition. Bonding attractive forces binding ‘atoms’ or ‘ions’ together to form a cpd (ionic and covalent) attractive forces holding ……. or. Compound. Compound atoms of different elements join together chemically

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Chapter 7

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  1. Chapter 7 Ionic and Metallic Bonding

  2. Bonding--definition Bonding • attractive forces binding ‘atoms’ or ‘ions’ together to form a cpd (ionic and covalent) • attractive forces holding …… or

  3. Compound Compound • atoms of different elements join together chemically • totally different in chem properties from the elements …. • Elements form cpds to increase in stability • Electrically neutral • A + B → A-----B bond Elements cpd • e.g. Na + Cl2 → NaCl

  4. bonding Form cpds Pure metal Intermolecular forces Metallic Bond Van derwaals Forces H bond Ionic bond Covalent bond Ion-dipole Dipole-dipole London dispersion

  5. 2 Types of Bonding—form cpds • Ionic bonding • transfer e- → cations and anions • Metal + nonmetal(s) • Form ionic cpds (e.g. NaCl) • 2. Covalent bonding • share e- (no ions) • Nonmetals only; (e.g. CO2, H2O) • form covalent cpds (molecular cpds)

  6. Compounds Covalent cpds or molecular cpd Ionic cpds formed by formed by Covalent bonds Ionic bonds Sharing e- Transfer of e- Metal + nonmetal(s) nonmetals e.g. MgO e.g. H2O

  7. 2 Types of Bonding— do not form cpds *3. Metallic bonding • in metallic elements • does not form cpds. *4. Hydrogen bonding • between H and O, N, or F atoms (among molecules) • does not form cpds

  8. Valence e- Valence e- • e- in the highest EL of an atoms. • # valence e- largely determines the chem properties of an element.

  9. Valence e- # of valence e- in an atom of (a representative element) = group # or the ones digit of the group #

  10. Valence e- 7.1

  11. The Octet Rule (1) The Octet Rule • Atoms of what type of elements tend to lose e-? metals: groups 1A, 2A, 3A, B • Atoms of what type of elements tend to gain e- ? Nonmetals: groups 5A, 6A, 7A

  12. The Octet Rule (2) In forming cpds, atoms tend to achieve the e- confign of a noble gas.

  13. Ionic Bonding Ionic bonding • transfer e- • Metal + nonmetal(s) • Metals (1A, 2A, 3A, transition) lose e- to form …→ cations • Nonmetals (5A, 6A, 7A) gained e- to form … • cations and anions attract each other → Ionic cpd

  14. Ionic Bonding Cation and anion attract each other by electrostatic force • ioniccpds [metal + nonmetal(s)] • e.g. Na → Na+ + e- (loss) Cl + e- → Cl- (gain) • Na+ ~~ Cl- Electrostatic attraction

  15. Formation of Ionic Cpds Formula Units (ionic cpds) • the lowest whole-# ratio of ions in an ionic cpd. • A chemical formula shows the kinds and #s of atoms in the smallest representative unit of a sub. e.g. NaCl is a formula unit of sodium chloride—1 Na+ bonded to 1 Cl-

  16. The Octet Rule (3) Losing valence e- • Atoms of metals tend to lose their valence e- • leaving a complete octet in the next-lower EL. • e .g. Na (1s22s22p63s1) loses 1 valence e ---- leave a Ne e-confign (1s22s22p6)→ Na+ Neon e- confign

  17. The Octet Rule (4) Gaining e- • Atoms of some non-metals tend to gain e- to achieve a complete octet. • e.g. Cl (1s22s22p6 3s23p5 ) achieve an e- confign of Ar (Cl- 1s22s22p6 3s23p6 ) after gaining 1 e- Ar e- confign

  18. Formation of Cations An atom lost valence e- produces a cation (+ve). e.g. Na → Na+ + e- Mg → Mg 2+ + 2 e- e.g. Al → cations

  19. Formation of Cations cations are produced by • the loss of valence e- from metal atoms. • The e- loss (ionization) of the Na atom Ne e- confign

  20. Formation of Cations The e- confign of the Na+is the same as that of a Ne atom. Na+

  21. Na+ and Ne Differences Similarity • same e- configuration • both octet

  22. Formation of Cations 1 unit of +ve charge 1 unit of –ve charge Na ion

  23. Formation of Cations • A Mg atom attains the e- confign of Neby losing both valence e-. • The loss of valence e- produces a Mg cation(Mg2+) with a charge of 2+. (2 units of –ve charge) (2 units of +ve charge)

  24. Formation of Cations • Cations of gp 1A 1+ • Cations of gp 2A elements 2+

  25. Formation of Anions The gain of e- by a neutral atom → an anion. • A particle derived from an atom (nonmetals) or a group of atoms • Carries -vecharge(s) after gaining e-. • many names of an anion ends in -ide. e.g. oxide, chloride, fluoride, sulfide, nitride, iodide,

  26. Formation of Anions

  27. Formation of Anions • A gain of 1 e- gives Cl an octet and converts a Cl atom into a chloride ion (Cl-). • the same e- confign as the noble gas Ar.

  28. Formation of Anions Both a Cl- and the Ar atom have an octet of e- in their highest occupied ELs.

  29. Formation of Anions In this eqn, each dot in the e- dot structure represents an e- in the valence shell in the e- confign diagram. 7 valence e- Octet

  30. Formation of Anions halide ions • ions produced when atoms of Cl and other halogens gain e-. • Fluorides (F-), chlorides, bromides, iodide • All halogen atoms need to gain only 1 e- to achieve the e- confign of a noble gas.

  31. Formation of Anions • O is in Gp 6A.

  32. Ionic Charges of SomeIons

  33. Anions in Binary Cpds

  34. Polyatomic Ions

  35. Formation of Anions 7.1

  36. Metal Ions with more than 1 Ionic Charges

  37. Highly Unequal Sharing • Ionic Bond • e- transfer results in the formation of 1 +ve ion and 1 -ve ion. • Metal ~ nonmetal • The bond formed by the 2 oppositely charged ions. Cation~~anion Electrostatic attraction

  38. A Model of Bonding • By forming bonds, atoms acquire an octet of e- and the stable e- confign of a noble gas. • Atoms are often more stable when they’re bonded in cpds than when they’re free atoms.

  39. Formation of Ionic Cpds Ionic Bonds • The electrostatic forces that hold ions together in ionic cpds are called ionic bonds.

  40. Physical Properties of

  41. Atomic View of Metallic Bonding • Each atom in this model of a Gp 2 metal releases its 2 valence e- into a sea of e- to be shared by all of the metal atoms. • Delocalized e-

  42. Sea of Valence e- • The valence e- of metal atoms are loosely held by the +vely charged nucleus. • In metallic bonding, metal atoms don't lose valence e-. • Not forming cpds

  43. Sea of Valence e- • metallic bond • Metal atoms release valence e- into a sea of e- shared by all of the metal atoms. • Attraction between e- sea and the metal atoms (cations)

  44. Atomic View of Metallic Bonding • Bonding in metals is not rigid. As a metal is struck by a hammer, the atoms slide thru the e- sea tonew positions while continuing to maintain their connections (bond) to each other. • The same ability to reorganize explains why metals …

  45. Properties That Reflect Metallic Bonding • Conductors of electricity • the valence e- are freely moving and is charged. • Electric current is a flow of e-

  46. Properties That Reflect Metallic Bonding • Metals and alloys are malleable • made into thin sheets

  47. Properties That Reflect Metallic Bonding • Metals are Ductile • can be drawn into wires.

  48. CST problem 1 When cations and anions join, they form what kind of chemical bond? A ionic B hydrogen C metallic D covalent

  49. CST problem 2 The reason salt crystals, such as KCl, hold together so well is because the cations are strongly attracted to A neighboring cations B the protons in the neighboring nucleus C free electrons in the crystals D neighboring anions.

  50. The End

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