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)

Non-metals share electrons with each other to complete their valence shells

COVALENT

balanced, stable.Good building

block

Non-polarPolar

hydrocarbons = CxHx

Polar Bonds

oxygen has stronger “attraction” for the electrons than hydrogen

oxygen has higher electronegativity

H

H

Oxygen

Water is a polar molecule

+ vs – poles

+

+

–

–

––

Hydrogen Bonding

H bonds

H

O

H Between the “negative-ish”

oxygen

and

The ”positive-ish” hydrogen

WEAKThere is strength in numbers