Philip DuttonUniversity of Windsor, Canada

Prentice-Hall © 2002

General ChemistryPrinciples and Modern Applications

Petrucci • Harwood • Herring

8th Edition

Chapter 9: The Periodic Table and Some Atomic Properties

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Contents

9-1 Classifying the Elements: The Periodic Law and the Periodic Table

9-2 Metals and Nonmetals and Their Ions

9-3 The Sizes of Atoms and Ions

9-4 Ionization Energy

9-5 Electron Affinity

9-6 Magnetic Properties

9-7 Periodic Properties of the Elements

Focus on The Periodic Law and Mercury

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9-1 Classifying the Elements: The Periodic Law and the Periodic Table

• 1869, Dimitri Mendeleev Lothar Meyer

When the elements are arranged in order of increasing atomic mass, certain sets of properties recur periodically.

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Periodic Law

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Mendeleev’s Periodic Table

1871

— = 44

— = 72— = 68— = 100

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Predicted Elements were Found

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X-Ray Spectra

• H.G.J. Moseley 1913–X-ray emission is explained

in terms of transitions in which e- drop into orbits close to the atomic nucleus.

–Correlated (Ka) frequencies to atomic number Z: (Ka) = a (Z – 1)2

–Used to predict new elements (43, 61, 75) later discovered.

Bohr atom and Moseley empirical formula

• Bohr:• 1913: Z-1 because one 1s electron is there.

• Moseley’s empirical formula:• 199-14

General ChemistryG. I. Csonka

Slide 8 of 35

22

221 2

111

1)( ZREEhKE H

HzZZh

RH 2152 11047.243

1

HzZK 215 11048.2

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The Periodic tableAlkali Metals

Alkaline Earths

Transition Metals

Halogens

Noble Gases

Lanthanides and Actinides

Main Group

Main Group

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9-2 Metals and Nonmetals and Their Ions

• Metals– Good conductors of heat and electricity.– Malleable and ductile.– Moderate to high melting points.

• Nonmetals– Nonconductors of heat and electricity.– Brittle solids.– Some are gases at room temperature.

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Metals Tend to Lose Electrons

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Nonmetals Tend to Gain Electrons

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Electron Configuration of Some Ions

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9-3 The Sizes of Atoms and Ions

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Atomic Radius

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Screening and Penetration

Zeff = Z – S

En = - RH n2

Zeff2

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Penetration and Shielding

Slater rules: For a 1s electron, S = 0.3.

For electrons in an s or p orbital with n > 1, the screening constant is given by

S = 1.00·N2 + 0.85·N1 + 0.35·N0N0 represents the number of other electrons in the same shell, N1 represents the number of electrons in the next smaller shell (n-1), and N2 is the number of electrons in other smaller shells

(n-2 and smaller).

The effective nuclear charge is

Zeff = Z - S

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Cationic Radii

Ne 131 pm

13]Ne[ s23]Ne[ s

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Anionic Radii

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Atomic and Ionic Radii

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9-4 Ionization Energy

Mg(g) → Mg+(g) + e-I1 = 738 kJ

Mg+(g) → Mg2+(g) + e- I2 = 1451 kJ

I1 = RH n2

Zeff12 S1 = 2 + 8·0.85 + 0.35 = 9.15

Zeff1 = 2.85

S2 = 2 + 8·0.85 = 8.80Zeff2 = 3.2 I2 = RH n2

Zeff22

Where n is the main quantum number, here it is 3. (3s2)

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First Ionization Energy

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Table 10.4 Ionization Energies of the Third-Period Elements (in kJ/mol)

I2 (Mg) vs. I3 (Mg)

7733

1451

I1 (Mg) vs. I1 (Al)

737.7 577.6

I1 (P) vs. I1 (S)

1012 999.6

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9-5 Electron Affinity

F(g) + e- → F-(g) EA = -328 kJ

F(1s22s22p5) + e- → F-(1s22s22p6)

Li(g) + e- → Li-(g) EA = -59.6 kJ

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First Electron Affinities

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Second Electron Affinities

O(g) + e- → O-(g) EA = -141 kJ

O-(g) + e- → O2-(g) EA = +744 kJ

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9-6 Magnetic Properties

• Diamagnetic atoms or ions:– All e- are paired.– Weakly repelled by a magnetic field.

• Paramagnetic atoms or ions:– Unpaired e-.– Attracted to an external magnetic field.

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Paramagnetism

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9-7 Periodic Properties of the Elements

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332266

Boiling Point

??

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Melting Points of Elements

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Melting Points of Compounds

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Reducing Ability of Group 1 and 2 Metals

2 K(s) + 2 H2O(l) → 2 K+ + 2 OH- + H2(g)

Ca(s) + 2 H2O(l) → Ca2+ + 2 OH- + H2(g)

I1 = 419 kJ

I1 = 590 kJ

I2 = 1145 kJ

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Oxidizing Abilities of the Halogens

2 Na + Cl2 → 2 NaCl

Cl2 + 2 I- → 2 Cl- + I2

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Acid Base Nature of Element Oxides

• Basic oxides or base anhydrides:Li2O(s) + H2O(l) → 2 Li+(aq) + 2 OH-(aq)

• Acidic oxides or acid anhydrides:SO2 (g) + H2O(l) → H2SO3(aq)

• Na2O and MgO yield basic solutions

• Cl2O, SO2 and P4O10 yield acidic solutions

• SiO2 dissolves in strong base, acidic oxide.

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Focus on The Periodic Law and Mercury

• Should be a solid.

• Relativistic shrinking of s-orbitals affects all heavy metals but is maximum with Hg.

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Chapter 10 Questions

1, 2, 18, 21, 27, 33, 39, 43, 51, 55