Atoms, Elements, and
Compounds
Chapter Fifteen: Molecules and
Compounds
• 15.1 Compounds and Chemical Bonds
• 15.2 Electrons and Chemical Bonds
Investigation 15A
Chemical Bonds
• How do atoms form chemical bonds with
other atoms?
15.1 Compounds and chemical
bonds
• A compound contains two or more
different elements that are chemically
bonded together.
15.1 Compounds and chemical
bonds
• A mixture contains two or more
elements and/or compounds that are not
chemically bonded together.
15.1 Molecules and covalent
bonds
• A chemical bond
forms when atoms
transfer or share
electrons.
• A covalent bond is
formed when atoms
share electrons.
15.1 Chemical formulas and
diagrams
• Molecules are represented by a chemical
formula.
• The chemical formula tells you the precise
number of each kind of atom in the molecule.
15.1 Structure and function
• The properties of a compound depend MUCH more on the
exact composition and structure (shape) of its molecule than
on the elements of which it is made.
15.1 Ionic bonds
• Ionic bonds are bonds in which
electrons are transferred from one atom
to another.
• Sodium and chlorine form an ionic bond
because the positive sodium ion is
attracted to the negative chloride ion.
15.1 Why chemical bonds form
• It takes energy to
separate atoms that
are bonded together.
• The same energy is
released when
chemical bonds form.
• Atoms form bonds to
reach a lower energy
state.