Chapter Two:

ATOMS, MOLECULES, AND IONS

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2-1 The Early History of Chemistryp39

2-2 Fundamental Chemical Lawsp41

Three Important Laws

Law of conservation of mass

Mass is neither created nor destroyed

Law of definite proportion

A given compound always contains exactly

the same proportion of elements by mass

Three Important Laws (continued)

Law of multiple proportions

When two elements form a series of compounds,

the ratios of the masses of the second element

that combine with 1 gram of the first element can

always be reduced to small whole numbers.

Ex 2.1 Illustrating the Law of MultipleProportions

P42

The following data were collected for several compounds of nitrogen

and oxygen:

Sow how these data illustrate the law of multiple proportions.Solution:

2-3 Dalton’s Atomic Theoryp43

Each element is made up of tiny particles called

atoms.

Dalton’s Atomic Theory (1808)

Dalton’s Atomic Theory (1808) (continued)

The atoms of a given element are identical; the

atoms of different elements are different in

some fundamental way or ways.

Dalton’s Atomic Theory (continued)

Chemical compounds are formed when atoms

combine with each other. A given compound

always has the same relative numbers and types of

atoms.

Dalton’s Atomic Theory (continued)

Chemical reactions involve reorganization of the atoms

- changes in the way they are bound together. The

atoms themselves are not changed in a chemical

reaction.

Avogadro’s Hypothesis (1811)

At the same temperature and pressure, equal volumes of

different gases contain the same number of particles.

5 liters of oxygen

5 liters of nitrogen

Same number of particles!

p43Representing Gay-Lussac’s Results

p45Representing Gay-Lussac’s Results

2-4 Early Experiments toCharacterize the Atom

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The Electron

Figure 2.7 A Cathode-ray tube. The fast-moving electrons excite thegas in the tube, causing a glow between the electrodes. The green colorin the photo is due to the response of the screen (coated with zincsulfide) to the electron beam.

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Early Experiments to Characterize the Atom

J. J. Thomson - postulated the existence of

electrons using cathode ray tubes.

Ernest Rutherford - explained the nuclear atom,

containing a dense nucleus with electrons

traveling around the nucleus at a large distance.

Cathode Ray Tube

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Milliken Oil Drop Experiment

2-5 The Modern View of AtomicStructure

The atom contains:

electrons

protons: found in the nucleus; positive charge

equal in magnitude to the electron’s negative

charge.

neutrons: found in the nucleus; no charge;

virtually same mass as a proton.

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p49The Nuclear Atom

Radioactivity

Rutherford’s Gold Foil Experiment

Nuclear Atom Viewed in Cross Sectionp50

Two Isotopes of Sodiump50

Ex 2.2 Writing the Symbols for AtomsP52

Write the symbol for the atom that has an atomic number

of 9 and a mass number of 19. How many electrons and

how many neutrons does this atom have?Solution:

2-6 Molecules and Ions p52

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Formation of Ionic Compounds

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Molecular vs. Ionic Compounds

Covalent Bonding

2-7 An Introduction to the PeriodicTable

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The Periodic Tablep56

2-8 Naming Simple Compoundsp57

Binary Ionic Compounds (Type I)p58

Naming Binary Ionic Compoundsp58

Ex 2.3 Naming Type I Binary CompoundsP58

Name each binary compound.

a. CsF b. AlCl3 c. LiH

Solution

P59

Ex 2.4 Formulas from Names forType I Binary Compounds

Given the following systematic names, write the formula

foe each compound:

a. Potassium iodide, b. Calcium oxide, c. Gallium bromide

Solution:

Binary Ionic Compounds (Type II)

p59Formulas from Names

Ex 2.5 Naming Type II Binary CompoundsP59

1. Give the systematic name for each of the following

compounds:

a. CuCl b. HgO c. Fe2O3

2. Given the following systematic names, write the

formula for each compound:

a. Manganese(IV) oxide

b. Lead(II) chloride

Solution: p60

Ex 2.6 Naming Binary CompoundsP60

1. Give the systematic name for each of the following

compounds:

a. CoBr2 b. CaCl2 c. Al2O3

2. Given the following systematic names, write the

formula for each compound:

a. Chromium(III) chloride

b. Gallium iodide

S0lution:

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Figure 2.22 The common cations and anions

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Ex 2.7 Naming Compounds ContainingPolyatomic Ions

P62

1. Give the systematic name for each of the followingcompounds:

a. Na2SO4, b. KH2PO4, c. Fe(NO3)3,d. Mn(OH)2, e. Na2SO3, f. Na2CO3

2. Given the following systematic names, write the formulafor each compound:a. Sodium hydrogen carbonate,b. Cesium perchloratec. Sodium hypochlorited. Sodium selenatee. Potassium bromate

Solution: p63

Ex 7.7 Solution (continued)

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Binary Covalent Compounds (Type III)p63

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N2O

NO

Ex 2.8 Naming Type III BinaryCompounds

P64

1. Name each of the following compounds:

a. PCl5, b. PCl3, c. SO2

2. From the following systematic names, write the formulafor each compound:

a. Sulfur hexafluoride, b. Sulfur trioxide,c. Carbon dioxide

Solution:p64

Flowchart for Naming Binary Compounds

Figure 2.23

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Overall Strategy for NamingChemical Compounds

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Figure 2.34

P65

Ex 2.9 Naming Various Types ofCompounds

1. Give the systematic name for each of the following

compounds:

a. P4O10, b. Nb2O5, c. Li2O2, d. Ti(NO3)4

2. Given the following systematic names, write the

formula for each compound:

a. Vanadium(V) fluoride, b. Dioxygen difluoride,

c. Rubidium peroxide, d. Gallium oxide

Solution:

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Ex 2.9 Solution (continued):p66

Flowchart for Naming Acids

Figure 2.25

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