Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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 Chemical Bonding: Basic Concepts Topic 11 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 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 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 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 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 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 Atomic View of Metallic Bonding • Bonding in metals is not rigid. • 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. • The same ability to reorganize explains why metals can be pulled into long, thin wires. Alloys • Substitutional • example is sterling silver • Interstitial • Example is carbon steel