–chemical reactions occur when bonds between the outermost parts of atoms are formed or broken
TRANSCRIPT
–Chemical reactions occur when bonds between the outermost parts of atoms are formed or broken
–Chemical reactions involve changes in matter, the making of new materials with new properties, and energy changes.
–Symbols represent elements, formulas describe compounds, chemical equations describe a chemical reaction
Items to the LEFT of the arrow in a chemical equation are called
REACTANTS.
2Na + Cl2 2NaCl
Items to the right of the
arrow are called
PRODUCTS.
Ex: 2Na + Cl2 2NaCl
Important NOTE:
No matter how many reactants and products are involved, all atoms present at the start of a reaction are present at the end.
THE TOTAL MASS OF THE REACTANTS MUST EQUAL THE TOTAL MASS OF PRODUCTS.
MATTER IS NEVER CREATED OR DESTROYED.
A number that tells how many molecules of a substance are involved in a
chemical reaction.
A coefficient of 1 is not written.
Subscripts• A subscript indicates how many
atoms of an element are in a compound
Ex. H2SO4
H= 2 S = 1 O = 4
Subscripts vs. Subscripts vs. CoefficientsCoefficients
+ -- used to separate two reactants or products.
(yields) Separates reactants and products.
Reactions that release heat.
Reactions that absorb heat.
A substance that speeds up chemical reactions.
A substance that slows down a chemical reaction.
Reactions that have hydrocarbons (CH4) and oxygen as reactants, and carbon dioxide and water as products.
Example:
C3H8 + 5O2 3CO2 + 4H2O
2Na + Cl2 2NaCl
Na2O + CO2 Na2CO3
Starts with one reactant and ends with 2 or more products.
2KClO3 2KCl + 3O2
2NaCl 2Na + Cl2
One compound and a free element that recombine to yield a new compound and new free element.
Fe + CuSO4 Cu + FeSO4
2Na + 2HCl H2 + 2NaCl
Starts with 2 compounds as reactants. These recombine to form 2 new compounds as products.
+ +
NaCl + AgNO3 NaNO3 + AgCl
KOH + HNO3 HOH + KNO3
C + O2 ----- CO2
2NaCl 2Na + Cl2
FeCl2 + K2S FeS + 2KCl
C2H4 + 3O2 2CO2 + 2H2O
2AlCl3 + 3Na2CO3 Al2(CO3)3 + 6NaCl
CS2 + 3O2 CO2 + 2SO2
3Fe + 4H2O Fe3O4 + 4H2
2AlCl3 2Al + 3Cl2
2Na + H2SO4 ---> Na2SO4 + H2
2Cr + 3O2 2CrO3