UNIT 2: Chemical Reactions

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UNIT 2 Chemical Reactions

• Chapter 3 Chemical Names, Formulas, and
  Equations
• Chapter 4 Classifying Compounds and Chemical
  Reactions

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Chapter 3 Chemical Names, Formulas, and Equations
UNIT 2
Chapter 3 Chemical Names, Formulas, and Equations
Chemical reactions are used in a variety of
sometimes surprising places. This photographer is
using a breathing apparatus that uses a chemical
reaction to recycle the air.
Why is the photographer using this type of
breathing apparatus?
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3.1 Ionic and Molecular Compounds
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and
Equations

• Many of the chemical compounds in products that
  people use at home, school, and work have
  properties that make them both beneficial and
  potentially dangerous.
• Chlorine compounds are both useful and hazardous.

• How is chlorine useful inswimming pools?

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Chemical Compounds
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and Equations

• Identify the molecular compounds and the
  ionic compounds in the objects below.

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Chemical Compounds
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and Equations

• Compounds are made of elements that are
  chemically combined in specific proportions.
• Two classifications that chemists use to
  categorize compounds are molecular compounds and
  ionic compounds.

Water is composed of molecules. Water molecules
consist of two hydrogen atoms bonded to one
oxygen atom.
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Molecular Compounds
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and Equations

• A molecule is a particle formed by two or more
  atoms joined by covalent bonds.
• A molecular compound is a compound formed of
  atoms of two or more elements that share
  electrons.
• The particles in a molecule are held together by
  covalent bonds.

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Ionic Compounds
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and Equations

• An ion is an atom or group of atoms with a
  positive or negative charge.
• An ionic compound is a compound composed of
  oppositely charged ions held together with strong
  ionic bonds.

A crystal of sodium chloride is structured so
that six chloride ions surround every sodium ion,
and six sodium ions surround every chloride ion.
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Section 3.1 Review
UNIT 2
Section 3.1
Chapter 3 Chemical Names, Formulas, and Equations

• Compounds can be classified as ionic or
  molecular. Ionic compounds and molecular
  compounds have characteristic properties that are
  a result of their structure at the atomic level.

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• Work with your group and come up with answers to
  the check your understanding questions on p.g.
  104.
• One member record the answers.
• You will probably need to go back and read some
  of section 3.1

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P.g. 104 Check your understanding

• 1. A molecule is the smallest independent unit of
  a molecular compound. It consists of atoms of
  different elements bonded together.
• 2. Two examples of molecular compounds are water
  and carbondioxide.
• 3. I agree with this statement because the bonds
  holding the atoms to one another in molecules
  are, in fact, very strong. However, the bonds
  holding molecules to one another in molecular
  compounds are relatively weak.

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• 4. Molecular compounds tend to boil and melt at
  relatively low temperatures because the bonds
  holding the molecules to one another in a solid
  are relatively weak and do not require a lot of
  energy to break.
• 5. An ion is an atom or group of atoms with a
  positive or negative charge. Possible examples
  include Na and Cl-
• 6. Two examples of ionic compounds are sodium
  chloride and calcium carbonate.

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• In your group discuss and record answers to P.g.
  105 questions 1,2,3,4 (one set of answers per
  group is fine).

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• Answers to What to Do Questions p.g. 105
• 1. The number in the upper right corner of the
  element cell is the common charge on ions of that
  element.
• 2. The charge on the ion is the same down a
  group. The charge is a positive number for the
  metals on the left side of the table and a
  negative number for non-metals on the right side
  of the table.
• Answers to What Did You Find Out? Questions
• 1. Recognize that the charge on the metals is
  positive and is 1 for Group 1, 2 for Group 2, 2-
  for Group 16, 1- for Group 17, and 0 for Group
  18.
• 2. It is not expected that elements from Group
  18, the noble gases, would form ionic compounds
  because they have a charge of zero and thus do
  not gain or lose electrons. Given that they are
  neutral, there is no strong attraction to
  positive or negative ions.

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• As a class we will read through the lab on P.g.
  106 107.
• In your groups prepare the chart on the following
  slide.
• One group member will record your results.
• You and your group will answer the questions on
  the conclude and apply section.

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Add odour, Molecular compounds should smell
strong. If it smells strong give it a score of 1.
Ionic compounds should smell weak, weak smell or
no smell give it a score of 0. DO NOT DIRECTLY
SMELL ANYTHING IN THE LAB! After completing all
other tests guess what your results would be for
melting and conductivity.
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• Complete the chart and hand it in along with
  answers to the conclude and apply on P.g. 107.
  Everyone must make a copy but you choose one
  group members copy to hand in.

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• Compound A Baking Soda - NaHCO3 - Ionic
• Compound B Glucose - C6H12O6 - Molecular
• Compound C Table salt - NaCl - Ionic
• Compound D Starch - C12H22O11 - Molecular

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Whats in a name?

• Read activity 3-2A, discuss with the people
  around you and then we will discuss as a class.

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What Did You Find Out? Questions P.g. 110

• 1. One way to distinguish between ionic and
  molecular compounds through naming is to look for
  prefixes such as mono- and di-, which
  indicate the number of each type of atom in a
  compound and are only used for molecular
  compounds. A second way to distinguish between
  ionic and molecular compounds is to look for
  Roman numerals that indicate the charge on a
  metallic ion in some ionic compounds.
• 2. The number of each type of atom present in a
  molecular compound is indicated through the use
  of prefixes in the name of the compound. These
  prefixes are not used in naming ionic compounds.

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3.2 Names of Ionic Compounds
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• Names of Binary Ionic Compounds
• A binary ionic compound is a compound composed of
  ions of one metal element and ions of one
  non-metal element joined by ionic bonds.
• The name of a binary ionic compound comes from
  the names of its elements.
• How is a binary ionic compound named?

magnesium sulfide
aluminum fluoride
sodium chloride
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• The metallic element (positive ion) comes first
  in the name
• The end of the name of the non-metallic element
  is changed to -ide ( Ex.) sodium chloride)

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• On your own or with a partner review pages 111
  -112 and answer questions 7-10 on p.g. 113. (new
  piece of paper)

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Interpreting the Chemical Formula of an Ionic
Compound
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• The chemical formula of a binary ionic compound
  contains element symbols to identify each ion.
• The positively charged ion is named first, and
  the negatively charged ion is named second.
• Subscripts are used to indicate the ratio of each
  type of ion in the compound.
• What does each symbol in the formula mean?

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• Read and consider 3-2B on p.g. 112. talk out the
  questions with those around you. As a class we
  will discuss 3-2B on p.g. 112.

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Writing Formulas of Ionic Compounds
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• Although an ionic compound is made up of ions,
  the compound itself is electrically neutral.
• The periodic table can be used to determine the
  charges of some ions.

What charges do ions in Group 1, Group 2, and
Groups 3-7 have?
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Sample Problem, P.g. 114 - 115
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• Complete the practice problems on P.g. 115
• 1-3 on a piece of paper separate from your
  notes! (can be the same as you used for p.g. 113)
• Once you are finished get the worksheet on Bionic
  compounds, fill in the formula section and then
  also write in the name of the compound next to it.

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Answers to page 113

• 7. Atoms of elements in Group 17 form ions with a
  charge of 1-. Atoms of elements in Group 16 form
  ions with a charge of 2-. Atoms of elements in
  Group 15 form ions with a charge of 3-.
• 8. (a) Binary it consists of two elements only
• (b) Binary it consists of two elements only
• (c) Not binary it consists of three elements
• (d) Not binary it consists of three elements

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• 9. (a) rubidium bromide
• (b) magnesium oxide
• (c) strontium fluoride
• 10. (a) potassium bromide
• (b) magnesium chloride
• (c) magnesium selenide
• (d) sodium sulfide
• (e) lithium nitride
• (f) aluminum bromide
• (g) beryllium fluoride
• (h) rubidium bromide

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• Go over answers to p.g. 115 as a class.

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• Worksheets Binary Ionic compounds

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• Activity 13 Building Compounds
• Questions
• What are binary ionic compounds composed of?
• How is the formula for a binary ionic compound
  written?
• Materials
• chemistry tiles set, various forms are
  available
• Procedure
• Rules for using chemistry tiles
• You must have a rectangle when you are done.
• Positive ions go on the left.
• Negative ions go on the right.
• When writing the formula, write the positive
  ion followed by a
• subscript that tells how many tiles are used and
  then the negative ion
• followed by a subscript that tells how many tiles
  are used.

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Multivalent Metals
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• Some metals are multivalent metals, which means
  that they can have more than one charge.
• When naming a compound that contains a
  multivalent ion, you must include a Roman numeral
  to show which charge the ion has.
• How can you use the periodic table to determine
  if an ion is a multivalent metal?

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• Go over Sample problem p.g. 117 as a class
• P.g. 117 questions 11, 12.
• Practice problems 4, 5.

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Ionic Compounds Containing Polyatomic Ions
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• Compounds containing polyatomic ions are not
  binary compounds because they contain at least
  three elements.
• Compounds containing polyatomic ions are named by
  writing the name of the positive ion followed by
  the name of the negative ion.

CaCO3
O22-
NH4
CO3-
Calcium carbonate is an ionic compound, but it is
not a binary ionic compound.
NO3-
Polyatomic ions are made up of more than one
atom. The polyatomic ions above are ammonium,
nitrate, peroxide, and carbonate.
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Ionic Compounds Containing Polyatomic Ions
UNIT 2
Section 3.2
Chapter 3 Chemical Names, Formulas, and Equations

• Which polyatomic ion is found in seashells?

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• Go over sample problem on p.g.118 as a class,
• Ionic card game.
• Homework Worksheet Binary Ionic Compounds
• Practice problems p.g. 119 6-8
• Test second class next week?