ORGANIC COMPOUNDS AND
THE ATOMIC PROPERTIES OF CARBON
Methane (natural gas)
Acetic Acid (in vinegar)
In the early 19
century, many prominent thinkers believed that an unobservable spiritual energy, a “vital force,”
existed within compounds from living things, which made them impossible to synthesize and fundamentally
different from compounds of the mineral world. The finding that urea (present in mammal urine) could be
synthesized from inorganic ammonium cyanate led to the downfall of vitalism.
a) Carbon’s electronegativity is midway between the most metallic and nonmetallic elements of period 2. To attain
a filled outer shell, carbon forms covalent bonds to other atoms in molecules (e.g., methane, CH
covalent solids (e.g., diamond) and polyatomic ions (e.g., carbonate, CO
b) Since carbon has 4 valence shell electrons, it forms four covalent bonds to attain an octet.
c) Two noble gas configurations, He and Ne, are equally near carbon’s configuration. To reach the He
configuration, the carbon atom must lose 4 electrons, requiring too much energy to form the C
cation. This is
confirmed by the fact that the value of the ionization energy for carbon is very high. To reach the Ne
configuration, the carbon atom must gain 4 electrons, also requiring too much energy to form the C
fact that a carbon anion is unlikely to form is supported by carbon’s electron affinity. The other possible ions
would not have a stable noble gas configuration.
d) Carbon is able to bond to itself extensively because carbon’s small size allows for closer approach and greater
orbital overlap. The greater orbital overlap results in a strong, stable bond.
e) The C-C bond is short enough to allow the sideways overlap of unhybridized
orbitals on neighboring C
atoms. The sideways overlap of
orbitals results in double and triple bonds.
a) The elements that most frequently bond to carbon are other carbon atoms, hydrogen, oxygen, nitrogen,
phosphorus, sulfur, and the halogens, F, Cl, Br, and I.
b) In organic compounds, heteroatoms are defined as atoms of any element other than carbon and hydrogen. The
O, N, P, S, F, Cl, Br, and I
listed in part a) are heteroatoms.
c) Elements more electronegative than carbon are N, O, F, Cl, and Br. Elements less electronegative than carbon
are H and P. Sulfur and iodine have the same electronegativity as carbon.
d) The more types of atoms that can bond to carbon, the greater the variety of organic compounds that are
Atomic and bonding properties produce three crucial differences between C and Si. Si is larger, forms weaker
bonds, and unlike C, has d orbitals available.
Oxidation states of carbon range from -4 to +4.
In carbon dioxide (CO
) carbon has a +4 oxidation state. In
), carbon has a -4 oxidation state.