What is responsible for bonding?  The electron.  Electrons whip around atoms all the time.  When atoms come near enough to each other, it is possible that electrons may be either transferred or shared between the atoms.  This only happens if the atoms involved have a reason to bond.  What are their reasons?      Nature seems to crave stability.  This stability comes from having the least possible amount of energy.
ANALOGY: A rock sitting on the side of a hill will tend to roll down the hill, NOT up the hill.  Once it's at the bottom of the hill, it is "happy", or more stable. Similarly,  atoms can become more stable by bonding.

Which atoms "want" to do what?  The periodic table at the top of this page can give us clues about how atoms will act.  The boxes in white represent METALS.  The gray boxes are NONMETALS.  The blackened boxes are sort of like both, and are called metalliods or semiconductors.   Lastly, the farthest right column is the NOBLE GAS column.  The noble gases are already very stable, and therefore reluctant to form any bonds at all.

Metals tend to lose electrons to become stable.  Nonmetals tend to gain electrons to become stable.  For this reason, compounds of metals with nonmetals are common.

Fill in the empty boxes:

DRAWING:
NAME & SYMBOL	carbon (C)	fluorine (F)	lithium (Li)	sodium (Na)	oxygen (O)	nitrogen (N)	sulfur (S)	hydrogen (H)
METAL or NONMETAL
column #
want to GAIN or LOSE electron(s)