WHEN ATOMS COLLIDE …
 When two or more atoms come into contact with the correct amount of energy, they will bond together to form a
molecule.
 When bonds are formed, valence electrons will either shared or transferred between the atoms.
 Differences exist in an atoms attraction for the electrons. Some atoms have a stronger attraction (hold) on the electrons
than other atoms.
 This results in electrons being equally shared, unequally shared or transferred completely from one atom to another.
TYPES OF MOLECULES…
Non-Polar Covalent
Non-Polar Covalent
Ionic
equal sharing of valence electrons
unequal sharing of valence electrons
complete transfer of valence electrons
perfectly symmetrical shaped molecule
asymmetrical shaped molecule
oppositely charged particles
unattractive to other molecules (not sticky)
attractive to other molecules (not
sticky)
attracted to other ions
very sticky
What is an ion again?
A charged atom
POSITIVE ION


FEWER electrons (negative) than protons (positive)
called a CATION
NEUTRAL ATOM

equal number of protons and electrons
NEGATIVE ION

MORE electrons (negative) than protons (positive)

called an ANION
WHY DOES BONDING MATTER?
Depending on the type of bonding taking place, the observed physical properties will change.
Here are a few examples:
low melting point
low solubility
high melting point
high solubility
MOLECULE LEWIS STRUCTURE
H2O
CO2
NaCl
NH3
Ca(OH)2
BONDING TYPE
PROPERTIES & MOLECULAR SHAPE
polar covalent





polar due to unequal sharing of electrons
bent shape (asymmetrical)
medium melting point
soluble in water
may look like a crystal when solid
non-polar covalent





non-polar due to equal sharing of electrons
linear shape (symmetrical)
very low melting point
low solubility in water
looks like a powder when solid
ionic




ionic due to oppositely charged ions
very high melting point
high solubility in water
looks like a crystal when solid
polar covalent





polar due unequal sharing of electrons
asymmetrical shape (like a pyramid)
medium melting point
soluble in water
may look like a crystal when solid
ionic




ionic due to oppositely charged ions
very high melting point
high water solubility
looks like a crystal when solid