Chapter 2 – The Chemical Basis of Life I: Atoms, Molecules,
and Water
Chapter Outline
1. Atoms
2. Chemical bonds and
molecules
3. Chemical reactions
4. Properties of water
5. pH and buffers
Remember blue font color
marks important ideas and
bold marks terms to master
,2.1 Atoms
Section 2.1 Learning
Outcomes
1. Sketch the general
structure of atoms
2. Define orbital and electron
shell
3. Relate atomic structure to
the periodic table of the
elements
4. Quantify atomic mass using
units of daltons and moles
5. Explain how a single
element may exist in 2 or
more forms, called isotopes
6. List the 4 elements that
make up most of the mass
of all living organisms
,2.1 Atoms
• Atoms are the smallest functional units of matter that form all
chemical substances
• Atoms cannot be further broken down into other substances by
ordinary chemical or physical means
• An element is a pure
substance made up of
only 1 kind of atom
• When 2 or more atoms
are bonded together, a
molecule is formed
, 2.1 Atoms
Atoms Are Composed of Subatomic Particles
• Three subatomic particles are found within an atom
• Protons
• positive charge (+)
• found in atomic nucleus
• Neutrons
• electrically neutral
• found in atomic nucleus
• Electrons
• negative charge (-)
• found in orbitals around the nucleus
• Protons and electrons are typically present in equal numbers,
giving the atom no net charge
• The number of neutrons can vary for a given atom
and Water
Chapter Outline
1. Atoms
2. Chemical bonds and
molecules
3. Chemical reactions
4. Properties of water
5. pH and buffers
Remember blue font color
marks important ideas and
bold marks terms to master
,2.1 Atoms
Section 2.1 Learning
Outcomes
1. Sketch the general
structure of atoms
2. Define orbital and electron
shell
3. Relate atomic structure to
the periodic table of the
elements
4. Quantify atomic mass using
units of daltons and moles
5. Explain how a single
element may exist in 2 or
more forms, called isotopes
6. List the 4 elements that
make up most of the mass
of all living organisms
,2.1 Atoms
• Atoms are the smallest functional units of matter that form all
chemical substances
• Atoms cannot be further broken down into other substances by
ordinary chemical or physical means
• An element is a pure
substance made up of
only 1 kind of atom
• When 2 or more atoms
are bonded together, a
molecule is formed
, 2.1 Atoms
Atoms Are Composed of Subatomic Particles
• Three subatomic particles are found within an atom
• Protons
• positive charge (+)
• found in atomic nucleus
• Neutrons
• electrically neutral
• found in atomic nucleus
• Electrons
• negative charge (-)
• found in orbitals around the nucleus
• Protons and electrons are typically present in equal numbers,
giving the atom no net charge
• The number of neutrons can vary for a given atom
