THE CHEMISTRY OF LIFE
The Nature of Matter
What do all of These Pictures
Have in Common?
And last, but not least…
GEICO’S Gecko!
MATTER
• All matter is made up of different
combinations of elements.
• Atom = the smallest quantity of an
element that still has the characteristics
of it.
• Atoms are made up of even smaller
(subatomic) particles: protons, neutrons,
and electrons.
THE NUCLEUS
• The core of an atom.
• It holds 99.9% of the
mass of the atom.
• It is small compared to
the whole atom.
– Most of atom is empty
space around the
nucleus.
– If nucleus of one atom
were 1cm wide, the size
of the atom would cover
30 football fields.
• It is made up of
Protons and
Neutrons.
• Electrons orbit
around the nucleus.
PROTONS
• Have a positive (+) charge.
• Found inside the nucleus of an atom.
• Each element has a different number of
protons.
• Atomic Number = the number of protons
in an atom.
• Proton # never changes in an element.
NEUTRONS
• Have no charge = “neutral”
• Found in the nucleus of an atom.
• Atoms of an element don’t always have
the same # of neutrons.
• These atoms are called isotopes.
ELECTRONS
•
•
•
•
•
Have a negative (-) charge.
Orbit around the nucleus.
It is always in motion.
Travels at the speed of light.
It is 2,000 times smaller than a Proton
or a Neutron.
– If the nucleus is 1cm wide, the Electrons
would be smaller than the width of a strand
of hair.
THE ATOM
• ProtonsHave a positive charge (+)
• NeutronsHave no charge
• ElectronsHave a negative charge (-)
• The nucleus = Protons + Neutrons.
• Surrounding the nucleus = Electrons.
ATOMIC NUMBER
• The number of Protons in the nucleus of
an atom.
• The number of Protons = the number of
Electrons.
ATOMIC MASS
• The number of Protons + the number of
Neutrons.
– Find the atomic mass of an atom that has
10 protons, 8 neutrons, and 10 electrons.
– An atom has:
• Atomic Number = 8
• Atomic Mass = 20
How many Protons, Neutrons and
Electrons does it have?
THE ATOM
• The nucleus = +
•
“Opposites
Attract”
charge.
• The electron cloud =
- charge.
• Nucleus and
electron cloud are
attracted to each
other.
ATOMIC STRUCTURE
ELECTRON ORBITS
•
•
•
•
1st orbit = 2 e2nd orbit = 8 e3rd orbit = 8 e4th orbit = 16 e-
• The atom is always
looking to fill up its
outermost orbit.
ELEMENTS
• Element = A pure
substance made up
of only one kind of
atom.
• Each element has a
unique atomic
number.
• Which one of these
is an element? 
PERIODIC TABLE OF
ELEMENTS
• Elements are
categorized by
atomic number =
number of protons.
• Who created the
Periodic Table of
Elements?

ISOTOPES
• IsotopesAtoms of an element that
have different number of neutrons.
– Ex. Carbon-12, Carbon-13, Carbon-14
• All isotopes of an element have the
same chemical properties:
– Same number of electrons.
STOP AND REVIEW
•
•
•
•
•
•
•
ATOM
ATOMIC NUCLEUS
PROTONS
NEUTRONS
ELECTRONS
ATOMIC NUMBER
ATOMIC MASS
• ATOMIC
STRUCTURE
• VALENCE
ELECTRONS
• ELEMENT
• PERIODIC TABLE
• ISOTOPES
COMPOUNDS
• Compound =
Substance made up
+
of atoms of two or
more different
elements.
• Compounds are
joined by chemical
bonds.
• They can be broken
down into simpler
Sodium Chloride = Table salt substances.
Sodiu
m
Chlorine
CHEMICAL BONDS
• Covalent Bond = Forms
when two or more atoms
share electrons to form a
molecule.
• If the electrons are
shared equally =
nonpolar bond.
• If electrons are NOT
shared equally = polar
bond.
– Ex. H2O (hydrogen
bonds)
– Who does it remind you
of?
MOLECULES
• Molecules = The structure that results when
two atoms are joined by covalent bonds.
• Physical and chemical characteristics are
different from the elements that make it up.
CHEMICAL BONDS
• Ionic Bond = One
atom pulls the
shared electrons
away from the other
atom. (greedy)
• Ion = An atom or
molecules that has
gained or lost one or
more electrons.
• Ex. Na+, Cl-
--Ionic bond between sodium (Na) and Chlorine
(Cl) = Na+ and Cl- ions
http://www.visionlearning.com/library/module_viewer.php?c3=&mid=55&ut=&l=e
http://www.sciencejoywagon.com/chemzone/lessonch/03bonding/dogbond/default.htm
IONIC BOND
• Na+ + Cl- = NaCl
(Sodium Chloride)
• Sodium Chloride =
Table salt
• Salt crystal
STOP AND REVIEW
• COMPOUNDS
• CHEMICAL BONDS
• COVALENT BOND
– NONPOLAR
– POLAR
• IONIC BOND
• ION
QUESTIONS
• What is the basic structure of an atom?
• Give one example of a compound?
• What is the difference between a
covalent bond and an ionic bond?
• Why do all isotopes of an element have
the same chemical properties?
QUESTIONS
• Two or more different atoms are
combined in definite proportions in any:
– A. Symbol
– B. Isotope
– C. Element
– D. Compound
QUESTIONS
• An atom may have a positive charge, a
negative charge, or be electrically
neutral. How does an atom develop a
negative charge?
– A. by gaining a neutron
– B. by gaining an electron
– C. by losing an electron