Atoms are the building blocks of all matter. Atoms are the
smallest particle that cannot be broken down. Atoms join with
others atoms to make everything.
Slide 3
Chemical Reactions often cause observable changes
Slide 4
Color Odor Release or Absorption of Heat Release or Absorption
of Light Release of Gas
Slide 5
Examples of Physical Changes *Melting ice *Dissolving salt
*Cutting paper
Slide 6
*No new product is formed *Substance just physically appears
different
Slide 7
Examples of Chemical Changes *Color change *Heat absorbed or
released *Formation of gas
*Elements are made of only one kind of atom *Elements are all
listed on the periodic table Examples of elements: Oxygen O Iron Fe
Sodium - Na
Slide 10
*Compounds are made of two or more elements chemically combined
Examples of compounds: Water H 2 O Baking soda NaHCO 3 Carbon
dioxide CO 2
Slide 11
NaHCO 3 This is the chemical formula for baking soda. *How many
elements are there? 4 Sodium(Na) Hydrogen(H) Carbon(C) Oxygen(O
)
Slide 12
NaHCO 3 This is the chemical formula for baking soda. *How many
total atoms are there? 6 1 - Sodium(Na) 1 - Hydrogen(H) 1 -
Carbon(C) 3 - Oxygen(O )
Slide 13
Matter can NOT be created Nor can it be destroyed Chemical
Equations MUST balance
Slide 14
The same number of atoms of each element must be in the
products that were in the reactants of a chemical equation.
Example: ReactantsProduct
Slide 15
Chemical reactions are represented on paper by chemical
equations. Example: 2 hydrogen gas (2H 2 ) can react (burn) with
oxygen gas (O 2 ) to form 2 water molecules(H 2 0).
Slide 16
yields subscript
Slide 17
Why do Chemical Equations have to balance?
Slide 18
Is this a balanced equation? Yes atoms in = atoms out
Slide 19
Balance the following equation:
Slide 20
Slide 21
We seem to be o.k. with our number of (C)carbon atoms in both
the reactants and products But, we have only half the (H)hydrogen
in our products as in our reactants.
Slide 22
2
Slide 23
*This has balanced our (C)carbon and (H)hydrogen atoms *But, we
now have 4 (O)oxygen atoms in our products, and only have 2 in our
reactants.
Slide 24
2
Slide 25
We have a balanced chemical equation for the reaction of
methane with oxygen.
