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