Chapter 3 Chemical Interactions Study Guide
1. A chemical change is a change in matter that produces new
2. A solid that forms from solution during a chemical reaction is a
3. Two observable characteristics of a chemical reaction are:
A. The production of new materials that are different from
those of the starting materials.
B. A change in energy. Every reaction involves a change in
energy. It is either absorbed or released. A common
indicator that energy has been absorbed or released is a
change in temperature,
4. An endothermic reaction absorbs energy in the form of heat.
An example is baking soda reacting with vinegar. 5. An exothermic reaction releases energy in the form of heat.
An example is fuel reacting with oxygen in airplane engines. 6. Chemical bonds are the force that holds atoms together.
Chemical reactions break down old bonds and new bonds form.
A chemical reaction is the effect of countless small changes. 7. A shorter, easier way to show chemical reactions using symbols
instead of words is a chemical equation.
8. Reactants are the materials you have at the beginning of a
9. Products are the materials you have at the end of a reaction. 10.You may have different numbers of reactants & products but
the reactants are always first and the products are last.
Fe + S ? FeS CaCO ? CaO + CO2
Reactant + Reactant ? Product
11.Numbers called subscripts show the number of atoms of an
element in a molecule or the ratio of elements in a compound. 12.Coefficients tell how many atoms of molecules are involved
during a reaction.
13. In NaCl there are 2 atoms. Be able to count the number of
atoms in elements or molecules.
14.The Principle of Conservation of Mass states that during a
chemical reaction, matter is not created or destroyed. At the
end of a chemical reaction, the total mass of the products must
equal the total mass of the reactants.
15.Chemical reactions are classified by what happens to the
reactants and the products.
16.There are 3 kinds of chemical reactions:
A. Synthesis Two or substances combine to make a more
complex compound. 2SO + O2 + HO?2HSO2224
B. Decomposition Compounds are broken down into simpler
products. 2HO?2HO +O 2222
C. Replacement One element replaces another in a compound,
or two elements in different compounds trade places.
2CuO + C ?2Cu + CO 2
Review the Workbook pp. 25-32 and your vocabulary quiz. There will be a question balancing an equation.