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Mastering Chemistry

Mastering Chemistry. Registration and Log In Course ID: MCWICKUN89304. Basic Concepts of Chemical Bonding. Chapter 8. What’s Ahead (p 297). Three types of bonds Lewis symbols Ionic bonding Octet rule Lattice energy in ionic compounds. Three Types of Chemical Bonds. Ionic bond

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Mastering Chemistry

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  1. Mastering Chemistry • Registration and Log In • Course ID: • MCWICKUN89304

  2. Basic Concepts of Chemical Bonding Chapter 8

  3. What’s Ahead (p 297) • Three types of bonds • Lewis symbols • Ionic bonding • Octet rule • Lattice energy in ionic compounds

  4. Three Types of Chemical Bonds • Ionic bond • Transfer of electrons • Between metal and nonmetal ions • Covalent bond • Sharing of pairs of electrons • Between nonmetal atoms • Metallic bond • Bonding electrons relatively free to move

  5. Group e- configuration # of valence e- ns1 1 1A 2A ns2 2 3A ns2np1 3 4A ns2np2 4 5A ns2np3 5 6A ns2np4 6 7A ns2np5 7 Valence electrons: outer shell electrons of an atom; valence electrons participate in chemical bonding.

  6. Table 8.1 Show only valence electrons!

  7. Ionic Bonding Na (s) + ½ Cl2 (g) → NaCl (s) ΔHfo = −410.9 kJ

  8. The Crystal Structure of Sodium Chloride Fig 8.3

  9. - - - - + Li+ Li Li Li+ + e- e- + Li+ Li+ + F F F F F F The Ionic Bond [He] [Ne] 1s22s1 1s22s22p5 1s2 1s22s22p6 LiF(s) Octet Rule: Atoms tend to gain, lose, or share electrons until surrounded by 8 valence electrons

  10. Eel = k Q+Q- d Electrostatic (Lattice) Energy Lattice energy (E): the energy required to completely separate one mole of a solid ionic compound into gaseous ions Q+ is the charge on the cation Q- is the charge on the anion d is the distance between the ions Eqn. [8.4] • Lattice energy (E): • increases as Q increases and/or • increases as d decreases

  11. Electron Configurations of Cations and Anions of Representative Elements Metal atoms lose electrons so that cation has a noble-gas outer electron configuration Nonmetal atoms gain electrons so that anion has a noble-gas outer electron configuration

  12. -1 -2 -3 +1 +2 +3 Cations and Anions Of Representative Elements

  13. Electron Configurations of Cations of Transition Metals When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals. “First in, first out” Fe: [Ar]4s23d6 Mn: [Ar]4s23d5 Fe2+: [Ar]4s03d6 or [Ar]3d6 Mn2+: [Ar]4s03d5 or [Ar]3d5 Fe3+: [Ar]4s03d5 or [Ar]3d5

  14. Three Types of Chemical Bonds • Ionic bond • Transfer of electrons • Between metal and nonmetal ions • Metallic bond • Bonding electrons relatively free to move • Covalent bond • Sharing of electrons • Between nonmetal atoms

  15. Electron-Sea Model nucleus & core e- mobile “sea” of valence e- • Metallic Crystals • Lattice points occupied by metal atoms • Held together by metallic bonds • Soft to hard, low to high melting point • Good conductors of heat and electricity Cross Section of a Metallic Crystal

  16. Covalent Bonding • Objectives: • Characteristic properties • Lewis structures • Multiple bonds • Bond polarity and electronegativity

  17. Covalent Bonding • Atoms share pairs of electrons • Several electrostatic interactions in these bonds: • Attractions between electrons and nuclei • Repulsions between electrons • Repulsions between nuclei

  18. Change in electron density as two hydrogen atoms approach each other

  19. Why should two atoms share electrons? + 8e- 8e- 7e- 7e- F F F F F F F F lonepairs lonepairs single covalent bond single covalent bond lonepairs lonepairs Covalent Bond Lewis structure of F2

  20. single covalent bonds H H H H or H H O O O C O C O O double bonds O N N N N triple bond Lewis structure of water + + Double bond– two atoms share two pairs of electrons or Triple bond– two atoms share three pairs of electrons or

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