General Chemistry M R NaimiJamal Faculty of Chemistry

General Chemistry M. R. Naimi-Jamal Faculty of Chemistry Iran University of Science & Technology

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.

Metals Tend to Lose Electrons

Nonmetals Tend to Gain Electrons

Electron Configuration of Some Ions

The Sizes of Atoms and Ions

Atomic Radius

Screening and Penetration Zeff = Z – S Zeff 2 En = - RH 2 n

Cationic Radii

Anionic Radii

Atomic and Ionic Radii

Interionic Forces

Ionization Energy Mg(g) → Mg+(g) + e- I 1 = 738 k. J Mg+(g) → Mg 2+(g) + e- I 2 = 1451 k. J

First Ionization Energy

Ionization Energy

Table 10. 4 Ionization Energies of the Third-Period Elements (in k. J/mol) 737. 7 577. 6 1012 999. 6 1451 7733 I 2 (Mg) vs. I 3 (Mg) I 1 (Mg) vs. I 1 (Al) I 1 (P) vs. I 1 (S)

Electron Affinity F(g) + e- → F-(g) F (1 s 22 p 5) + EA = -328 k. J e- → Li(g) + e- → Li-(g) - F (1 s 22 p 6) EA = -59. 6 k. J

Second Electron Affinities O(g) + e- → O-(g) + e- → O 2 -(g) EA = -141 k. J EA = +744 k. J

First Electron Affinities

Electron Affinity

Periodic Properties of the Elements

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.

Paramagnetism

Crystal Structures

Unit Cells in the Cubic Crystal System

Hexagonal Close Packed (hcp)

Coordination Number

Sodium Chloride

Cesium Chloride

Lattice Energy • Ionic compounds are solids under normal conditions and their structures contain positive and negative ions arranged in a 3 -D lattice • Lattice energy, ∆Elattice, is the energy of formation of one mole of solid crystalline ionic compound when ions in the gas phase combine • Tells us the strength of ionic bonding in solids on ion sizes and ion charges

Energy Changes in the Formation of Ionic Crystals

Chapter 7 Questions 5, 8, 14, 17, 20 24, 31, 38, 47