The
CHEMISTRY
of Life
CHEMISTRY
is the foundation of
BIOLOGY.
Elements in the same column have
the same valence & similar
chemical properties
REACTIVITY
• Atoms tend to
• complete a partially filled valence shell
or
• empty a partially filled valence shell
–
–
REACTION (Bond formation)
–
Biological Bonds
–
–
H2 (hydrogen gas)
Biological systems are composed of
primarily non-metals (CNOPSH)
hydrocarbons = CxHx
Non-metals share electrons with each
other to complete their valence shells
COVALENT
Polar
Non-polar
balanced, stable.
Good building block
Polar Bonds
oxygen has stronger
“attraction” for the
electrons than hydrogen
+
oxygen has higher
electronegativity
–
H
–
Oxygen
Water is a polar molecule
–
H
+ vs – poles
+
–
Hydrogen Bonding
WEAK
There is strength in numbers
H
H
O
Between
the “negative-ish”
oxygen
and
The ”positive-ish”
hydrogen
H bonds