1 / 36

FORMAL CHARGE

. . . . :. N. N. :. H. . . H. FORMAL CHARGE. Unbonded. Bonded. Number of All One half of = valence electrons unshared + all shared

maja
Download Presentation

FORMAL CHARGE

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. .. . . . : N N : H . . H FORMAL CHARGE Unbonded Bonded Number of All One half of = valence electrons unshared + all shared in the neutral electrons electrons atom Formal Charge . NH2- . 6e- 5e- ( Formal Charge = 5 - 4 - 2 = -1 )

  2. When drawing a Lewis Diagram remember these rules. LEWIS DIAGRAMS SHOW IT ALL ! - all atomsincluding hydrogens - all bonds (lines not dots ) - all unshared pairs ( dots ) - allformal charges - all atoms with octets ( except H ) - the correct number of electrons ( count! )

  3. Rumus Kimia • Rumus empirik • Rumus Molekul • Rumus struktur • Rumus struktur lengkap • Rumus struktur panjang (expanded) • Rumus struktur termampatkan (condensed)

  4. Rumus Struktur pada senyawa siklis – sikloheksana • Expanded formula

  5. Rumus Struktur pada senyawa siklis – sikloheksana • Polygon formula(condensed formula)

  6. Rumus Struktur pada senyawa siklis – sikloheksana • Condensed formula

  7. Contoh Molekul siklis

  8. Beberapa cara penulisan struktur

  9. Molekul polar dan Nonpolar • To determine if a molecule is polar, we need to determine • if the molecule has polar bonds • the arrangement of these bonds in space • Molecular dipole moment (): the vector sum of the individual bond dipole moments in a molecule • reported in debyes (D)

  10. are due to differences in electronegativity. depend on the amount of charge and distance of separation. In debyes,  = 4.8 x (electron charge) x d(angstroms) Bond Dipole Moments

  11. Molecular Dipole Moments • Depend on bond polarity and bond angles. • Vector sum of the bond dipole moments. • Lone pairs of electrons contribute to the dipole moment.

  12. Polar and Nonpolar Molecules • these molecules have polar bonds, but each has a zero dipole moment

  13. Polar and Nonpolar Molecules • these molecules have polar bonds and are polar molecules

  14. Polar and Nonpolar Molecules • formaldehyde has polar bonds and is a polar molecule

  15. Intermolecular Forces • Strength of attractions between molecules influence m.p., b.p., and solubility; esp. for solids and liquids. • Classification depends on structure. • Dipole-dipole interactions • London dispersions • Hydrogen bonding

  16. Dipole-Dipole =>

  17. Dipole-Dipole Forces • Between polar molecules • Positive end of one molecule aligns with negative end of another molecule. • Lower energy than repulsions, so net force is attractive. • Larger dipoles cause higher boiling points and higher heats of vaporization.

  18. => London Dispersions • Between nonpolar molecules • Temporary dipole-dipole interactions • Larger atoms are more polarizable. • Branching lowers b.p. because of decreased surface contact between molecules.

  19. Dispersions =>

  20. Hydrogen Bonding • Strong dipole-dipole attraction • Organic molecule must have N-H or O-H. • The hydrogen from one molecule is strongly attracted to a lone pair of electrons on the other molecule. • O-H more polar than N-H, so stronger hydrogen bonding

  21. H Bonds

  22. Boiling Points and Intermolecular Forces

  23. ASAM DAN BASA

  24. Brønsted-Lowry Theory of Acids and Bases • Acid: Proton Donor • Base: Proton Acceptor Conjugate Acid: Base + Proton Conjugate Base: Acid - Proton

  25. Strong Acids and Bases • Strong acid - completely ionized in aqueous solution. Examples are: • HCl, HBr, HI, HNO3, HClO4, and H2SO4 • Strong base - completely ionized in aqueous solution. Examples are: • LiOH, NaOH, KOH, Ca(OH)2, and Ba(OH)2

  26. Weak Acids and Bases • Acetic acid is a weak acid • it is incompletely ionized in aqueous solution

  27. Lewis Theory of Acids and Bases • Acid: Electron-Pair Acceptor • Electrophile • Base: Electron-Pair Donor • Nucleophile

  28. Weak Acids and Bases • The equation for the ionization of a weak acid, HA, in water and the acid ionization constant, Ka, for this equilibrium are

  29. Weak Acids and Bases

  30. Acidity Constant (Ka)

  31. pKa pKa = - log Ka Strong acid = large Ka = small pKa Weak acid = small Ka = large pKa

  32. Relative Acid Strength

  33. Acid Strength • Strong Acid • Conjugate base is weak • pKa is small • Weak Acid • Conjugate base is strong • pKa is large

  34. Base Strength • Strong Base • Conjugate acid is weak • pKa is large • Weak Base • Conjugate acid is strong • pKa is small

  35. Position of equilibrium • Favors reaction of the stronger acid and stronger base to give the weaker acid and weaker base

  36. Position of equilibrium • Stronger acid and stronger base react to give weaker acid and weaker base

More Related