Chapter 2

Book L

Chemical Reactions

Name ______Teachers’ Copy______

Class ______

Test Date ______

Chapter 2 –Chemical Reactions Outline

Section 1-Forming New Substances P. 28 - 31

I. Chemical Reactions

*Notes-A ______Chemical Reaction____ is a process in which one or more substances change to make one or more new substances. Milk souring, food being digested, and a match burning are all examples of chemical changes.

A. Signs of Chemical Reactions

List 4 signs of chemical reactions.

_____Change of color_

___Gas formation__

____Energy change____

____Solid formation__

B.  A Change of Properties

NaCl = table salt

II. Bonds: Holding Molecules Together

A.  Breaking and Making Bonds

*Notes-For a chemical bond to break, ___Energy_____ is required.

B.  New Bonds, New Substances

*Notes-A chlorine gas molecule is a ____diatomic______molecule. A chlorine molecule is made up of ___2_____ atoms of chlorine. Cl2

Chapter 2 –Chemical Reactions Outline

Section 2-Chemical Formulas and Equations p. 32 - 37

I.  Chemical Formulas

A ______Chemical Formula______is a shorthand way to use chemical symbols and numbers to represent a substance.

*Notes-A ______Subscript______is a number written below and to the right of a chemical symbol. C6H12O6 The 6, 12, and 6 are all subscripts.

*To find the number of atoms in a compound you should __add____ the subscripts.

*Notes-If there is no subscript, only __1_____ atom of that element is present.

*In ZnCl2 there are __3_____ atoms because 1+2 = 3.

A.  Writing Formulas for Covalent Compounds

*Notes-the prefix di means ___2______atoms in a compound.

*Notes-the prefix tri means ___3______atoms in a compound.

*Notes-dinitrogen trioxide would have ___2_ atoms of nitrogen and ___3___ atoms of oxygen. N2O3

B.  Writing Formulas for Ionic Compounds

II. Chemical Equations

A.  Describing Reactions by Using Equations

B.  From Reactants to Products

*Notes-A substance or molecule that participates in a reaction is called a ____Reactant______.

*Notes-The substance that forms in a chemical reaction is called a _____Product______. You produce a product in a chemical reaction.

C.  The Importance of Accuracy

D.  The Reason Equations Must be Balanced

*Notes-The Law of Conservation of Mass dictates that chemical equations must be balanced because atoms are never _____lost__or _____gained__in a chemical reaction.

E. How to Balance an Equation

*Coefficient

2H2 + O2 2H2O

*Reactants *Subscript *Yield Sign *Product

*Note-The ____coefficient______is the number that is placed in front of a chemical symbol or formula.

** You can change the coefficient, but NOT the subscript #.

Chapter 2 –Chemical Reactions Outline

Section 3-Types of Chemical Reactions p. 38 - 41

I.  Synthesis Reactions

*Notes- In a ______Synthesis Reaction_____ two or more substances combine to form one new substance.

*__2Na_____ + _Cl2______2NaCl______(SALT)

Sodium reacts with chlorine to form sodium chloride

II.  Decomposition Reactions

*Notes-In a ____Decomposition Reaction___ a single compound breaks down to form two or more compounds.

*____H2CO3______H2O______+ ____CO2_____ (SODA)

Carbonic acid decomposes to form water and carbon dioxide

III.  Single-Displacement Reactions

*Notes-In a _Single Displacement Reaction_ an element replaces another element that is a part of a compound.

*___Zn______+ ___2HCl______ZnCl2____ + ____H2______

Zinc replaces the hydrogen in hydrochloric acid to form zinc chloride and hydrogen

  1. Reactivity of Elements

IV. Double-Displacement Reactions

Sodium chloride + silver fluoride sodium fluoride + silver chloride

NaCl +AgF NaF + AgCl

Chapter 2 –Chemical Reactions Outline

Section 4-Energy and Rates of Chemical Reactions p. 42 - 47

I.  Reactions and Energy

  1. Exothermic Reactions

*Note-Exothermic Reactions give off______Energy______.EXIT-thermic

(energy released)

b. Endothermic Reactions

*Note-Endothermic Reactions “take in” energy. They need __Energy_____ to get started.

AND-othermic (energy absorbed)

c. The Law of Conservation of Energy

II.  Rates of Reactions

  1. Activation Energy
  2. Sources of Activation Energy

Exothermic Reaction Endothermic Reaction

*Notes-Complete these graphs with the information from page 45 in your book. Know them for the test!

III.  Factors Affecting Rates of Reactions

  1. Temperature
  2. Concentration
  3. Surface Area

*Notes-Grinding a powder can increase the rate of a ____Reaction______.

  1. Inhibitors
  2. Catalysts

*Notes-A ___Catalyst______lowers the activation energy of a reaction, which allows the reaction to happen more quickly.