Chapter 8 Chapter 8

Ionic Compounds Chemical Bond – the force that holds atoms together Cations are + electrons are lost Anions are - electrons are gained

Ionic bond The electrostatic force that holds oppositely charged particles together is referred to as an ionic bond It is a strong bond Results in crystal formation, high melting points, compounds are hard, rigid, and brittle.

An ionic compound whose aqueous solution conducts electricity is called an electrolyte Ionic Solids are not conductors Conductors when Molten or Dissolved

Lattice energy The energy released when one mole of the ions of an ionic compound come together is referred to as the lattice energy related to size of the ions Also affected by charge See table 8.3 page 220

Formula unit Monatomic ion Oxidation number – the apparent charge on an atom Polyatomic ion – see table 8-6 page 224 Oxyanion contains oxygen

Properties That Reflect Metallic Bonding Metals and alloys are malleable and ductile, and they conduct electricity. When a metal can be pounded or rolled into thin sheets, it is called malleable. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Properties That Reflect Metallic Bonding Ductile metals can be drawn into wires. For example, copper can be pulled into thin strands of wire and used in electric circuits. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Properties That Reflect Metallic Bonding Electrical conductivity is a measure of how easily electrons can flow through a material to produce an electric current. These properties —malleability, ductility, and electrical conductivity—are the result of the way that metal atoms bond with each other. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Sea of Valence Electrons The valence electrons of metal atoms are loosely held by the positively charged nucleus. Sometimes, metal atoms form ionic bonds with non-metals by losing one or more of their valence electrons and forming positive ions. However, in metallic bonding, metal atoms don't lose their valence electrons. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Sea of Valence Electrons Metal atoms release their valence electrons into a sea of electrons shared by all of the metal atoms. The bond that results from this shared pool of valence electrons is called a metallic bond. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Atomic View of Metallic Bonding Each atom in this model of a Group 2 metal releases its two valence electrons into a pool of electrons to be shared by all of the metal atoms. Chemical Bonding: Basic Concepts Topic 11 Topic 11

Atomic View of Metallic Bonding Bonding in metals is not rigid. The same ability to reorganize explains why metals can be pulled into long, thin wires. Chemical Bonding: Basic Concepts Topic 11 Topic 11 As a metal is struck by a hammer, the atoms slide through the electron sea to new positions while continuing to maintain their connections to each other.

Alloys Substitutional example is sterling silver Interstitial Example is carbon steel