Properties of Organic and Inorganic Compounds

1. Properties of Organic and Inorganic Compounds Experiment 1 Chem 121 Organic Chemistry Laboratory

2. What is ORGANIC CHEMISTRY?

3. Introduction • Vital force – ‘vitalism’ • Friedrich Wohler overthrew vitalism • Synthesis of urea from ammonium cyanate • Distinguishing feature: organic compounds all contain the CARBON atom

4. What is ORGANIC chemistry? • the study of carbon containing compounds • Other elements in organic compounds: H, O, N, S, P, Cl, Br, I and other transition metals • Why Carbon? • Can share four valence electrons • Form strong covalent bonds • Form rings and long chains, e.g. benzene and DNA

5. Definition of terms • Ionic compounds: compounds made up of a metal cation and a nonmetal anion • e.g. NaCl, KNO3 • Intramolecular forces of attraction: forces existing within molecules that holds the atoms together • e.g. Ionic bond, covalent bond, metallic bond • Intermolecular forces of attraction: forces existing between molecules

6. Intermolecular Forces of Attraction • Ion-dipole • Between an ionic compound and a polar compound • e.g. NaCl dissolved in water • Dipole-dipole • Between two polar compounds • e.g. HCl dissolved in water

7. Hydrogen Bonding • Requirement: H atoms bonded to F, O, N • Strongest intermolecular force • e.g. NH3 in H2O • London dispersion forces/van der Waals forces • Between two NONPOLAR compounds • Weakest intermolecular force; present in all organic molecules

8. The larger the size of the organic compound, the larger the London dispersion forces.

9. Properties of Organic Compounds • Flammable • Due to the C-C bond energies in organic compounds • Energy released is in the form of heat • Ethanol vs. Water • Ethanol – produces the distinct blue flame • Water – smothers flame instead of generating one

10. Charring • also known as burning, scorching • organic compounds are sensitive to heat • End result of charring: elemental C • Sucrose • disaccharide • common ingredient in sweet foods like ice cream, candy • also works as a food preservative

11. IMF of sucrose: London dispersion force • IMF of NaCl and CaCO3: no intermolecular force, but intramolecular (IONIC BOND) • Remember always: Intramolecular forces are way STRONGER than intermolecular forces.

12. Solubility • relies on the intermolecular forces of organic compounds • ‘like dissolves like’ • Polar solvents dissolve in polar solutes. • Nonpolar solvents dissolve in nonpolar solutes. • Organic compounds = mostly nonpolar • It only follows that most organic compounds are soluble in organic solvents.

13. Naphthalene in ether • No ionic bonds, just pure London dispersion forces • Naphthalene in water • Water is capable of hydrogen bonding; naphthalene cannot

14. Electrical Conductivity • Electrical conductivity is only possible when a compound contains charged particles (i.e. an electrolyte) • e.g. NaCl, NaNO3 are electrolytes • Since most organic compounds are molecular, not ionic, it does not conduct electricity.

15. 1 M NaCl • hexane • 1 M sucrose • 1 M ethanol

16. Summary • Organic chemistry is the study of carbon compounds. • Organic compounds have the ff properties: • Flammable • Combustible • Immiscble in polar solvents like water • Non-electrolytes; do not conduct electricity