CHAPTER TWO: ESSENTIAL CHEMISTRY FOR BIOLOGY
Only two things exist in the universe: matter and energy. All living and nonliving things consist of a
combination of matter and energy. Some substances have a little matter and a lot of energy and other
substances have a lot of matter and a little energy.
DEFINITION Force that changes matter.
TWO STATES POTENTIAL
MANY FORMS Including electrical, nuclear, chemical, heat and light.
DEFINITION Anything that occupies space and has mass. All forms of matter are composed of
atoms, including living things.
UNIT OF STRUCTURE KNOWN AS THE ATOM.
• STRUCTURE AND ORGANIZATION OF ATOMS
Atomic mass means the total mass of an atom but includes only the mass of the protons and neutrons.
Atomic number refers to the number of protons in an atom’s nucleus. An element is a group of atoms
that are all the same type (having the same atomic number).
• THE PERIODIC TABLE
This table is a classification system for all known forms of atoms (elements) including 92 naturally
occurring elements and a number (ever increasing) of synthetically produced elements.
Some atoms have large, unstable nuclei and over time they lose or gain the energy-equivalents of a
Their mass then varies from the standard form of the element that is listed on the Periodic Table,
but their proton number remains the same.
If their mass is different from the standard form of that particular element which is listed on the
Periodic Table, then we call the form of the atom with the mass variation an isotope of the standard
• HOW ATOMS BOND TOGETHER TO CREATE MOLECULES
COVALENT BONDS Called a sharing bond.
POLAR COVALENT A bond that is not totally neutral, rather it has areas of partial charge.
Water is an example.
IONIC BONDS Atoms lose their neutrality and gain a charge by losing or gaining electrons.
They become ions in the process.
Because water is a polar covalent molecule it can form energy associations with many different types
of atoms or molecules.
That is why we call it a good solvent.
DEFINITION OF pH Measure of the amount of free H+ (or lack thereof) in a solution.
pH SCALE 1-6.9 indicates an acid, 7 means that the solution is neutral and 7.1-14
indicates that the solution is alkaline (base or basic).
NEUTRAL Balanced. The +ions and –ions are equal.
ACID Releases an excess of H+ ions into solution.
ALKALINE (BASE) Releases an excess of OH- ions into solution.
BUFFER A chemical (usually a protein) that can resist a change in the environmental
pH. Helps maintain homeostasis.