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CHEMICAL BONDSCHEMICAL BONDS
CHAP 9CHAP 9
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For Science Fair Judges
Write a 1 – 2 page word-processed report evaluating 2 projects. If you are not a judge, you may submit this assignment for 15 extra-
credit points or as a lab make-up.
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Composition of Ionic Compounds
Common names:
“salt”→ sodium chloride
“lye” → sodium hydroxide
“rust” → iron oxide
“baking soda” → sodium bicarbonate
“chalk” → calcium carbonate
Fig. 9.12 Three substances containing sodium and some form of the carbonate ion
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Names for Ionic Compounds containing only two different elements
• Metal (positive) ion is written and spoken first
• Negative element is written/spoken second
• Subscripts used to produce an electrically
neutral compound
e.g. NaCl, CaO, KI, Fe2O3, CaC2
Fig 11.6 NaCl dissolving in water
Box Fig. 9.1 Conductivity tester for determining if a solution contains ions
Fact: Dissolving an ionic compound in waterresults in ions being pulled apart from the crystallattice to form free ions
+ −
Chapter 10
Chemical Reactions
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Homework for Chap 10Homework for Chap 10
Read p 253 – 257; 261 - 271
Applying the Concepts # 1 – 17
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A molecular formula shows the actual number of atoms of each element in the smallest unit of a substance
An empirical formula shows the simplest whole-number ratio of the atoms in a substance
H2OH2O
molecular empirical
C6H12O6 CH2O
O3 O
N2H4 NH2
Chemical FormulasChemical Formulas
Fig. 10.2 Several ways to express common molecules
3 ways of representing the reaction of H2 with O2 to form H2O
A process in which one or more substances is changed into one or more new substances is a chemical reaction
A chemical equation uses chemical symbols to show what happens during a chemical reaction
reactants products
Fig. 10.4 The Combustion of Charcoal
C + O2 → CO2
“Carbon reacts with oxygen to yield carbon dioxide”
Fig. 10.5 The meaning of subscripts and coefficients
Fig. 10.6 Illustration of the Law of Conservation of Mass
Fig. 10.8 Hydrocarbons and Carbohydrates
C8H18
C3H8
C12H22O11
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Types of Chemical ReactionsTypes of Chemical Reactions
1) Oxidation-Reduction (Redox)
2) Combination
3) Decomposition
4) Replacement
5) Ion Exchange
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Oxidation-Reduction Reactions
(electron transfer reactions)
2Mg (s) + O2 (g) 2MgO (s)
Mg is the reducing agent (supplies electrons)
O2 is the oxidizing agent (takes electrons)
Oxidation – an atom loses electrons
Reduction – an atom gains electrons
Fig. 10.9 Example of an oxidizing agent (“chlorine”)
Others:
1) Bleach
2) Hydrogen
peroxide
3) Oxygen
4) Ultraviolet
light
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Types of Chemical ReactionsTypes of Chemical Reactions
1) Oxidation-Reduction (Redox)
2) Combination
3) Decomposition
4) Replacement
5) Ion Exchange
Fig. 10.10 Iron combines with oxygen to form rust Fig. 10.10 Iron combines with oxygen to form rust (iron oxide)(iron oxide)
4 Fe (4 Fe (ss) + 3 O) + 3 O22 ( (gg) 2 Fe) 2 Fe22OO33 ( (ss))
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Types of Chemical ReactionsTypes of Chemical Reactions
1) Oxidation-Reduction (Redox)
2) Combination
3) Decomposition
4) Replacement
5) Ion Exchange
Fig. 10.11 Decomposition of Mercury Oxide
2 HgO (s) → 2 Hg (l) + O2 (g)heat