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

What is ORGANIC CHEMISTRY?

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

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

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

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

London dispersion forces/van der Waals forces 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

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

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

Charring Sucrose 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

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.

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.

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

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.

1 M sucrose 1 M ethanol 1 M NaCl hexane

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