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Notes
BIOCHEMISTRY
The Element Carbon
 Carbon is present in every cell of every living
organism on Earth
 Arguably the most important element because it
makes up a large portion of DNA
 Carbon has four valence electrons
 Makes four bonds
 Bonds in variety of patterns
 Single, double, triple
 Forms short covalent bonds = very strong
 Can make long chain molecules
Four Allotropes of Carbon
 Allotropes: forms of the same element with
different bonding patterns
 Four Allotropes of Carbon
1. Diamond
 Diamond: each C atom is bonded to 4 other
C atoms = tetrahedral shape

Hardest natural substance on Earth
2. Graphite
 Graphite: C is arranged in sheets or layers

Relatively soft
3. Amorphous
 Amorphous: no predictable arrangement


Comes from decomposition of living things
Ex. Charcoal
4. Fullerenes
 Fullerenes: ball-shaped arrangement

Like soccer ball
Polymers
 Polymers: large organic compounds made of
repeating units
 Made up of monomers
 Polymer = many parts (like beaded necklace)
 Monomer = one part (like 1 bead)
 Ex. Plastics, nylon, proteins, starches
Biological Polymers
 Proteins: polymers made up of many amino acids
 Protein = polymer
 Amino acid = monomer
 20 different amino acids in the human body with same
basic structure
 Amine end (NH2) and carboxylic acid end (COOH)
Continued…
 DNA: polymers made up of many nucleic
acids
 DNA = polymer
 Nucleic acid = monomer
Notes
BALANCING CHEMICAL
EQUATIONS
Balancing Chemical Equations
 Law of conservation of matter: matter is
neither created nor destroyed in chemical
reactions
 # of atoms of each element must be the same
before and after a chemical reaction
Examples
 Add coefficients before compounds to
balance
H2 + O2
H2O
Na +
NaCl
Cl2
C4H10 + O2
CO2
+
H2O
Types of Chemical Reactions
 2 parts to chemical reaction


Reactants = starting materials on left of arrow
Products = ending materials on right of arrow
1. Combination



2 or more reactants combine to form a single
product
A + B
AB
Li + OH
Continued…
2. Decomposition



1 reactant breaks up into 2 or more products
AB
A + B
NaCl
Continued…
3. Single replacement
 Single element displaces an element in a
compound
 A + BX
 Mg + CuSO4
AX + B
Continued…
4. Double replacement



Atoms from 2 different compounds replace each
other
AX + BY
BX + AY
LiCl + MgS
Continued…
5. Combustion






Combination of O2 with substance
Releases heat (burning)
X + O2
Xa O b
Al + O2
Hydrocarbon + O2
C2 H 6 + O 2
CO2 + H2O