Ionic Compounds and Metals

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Ionic Compounds and Metals

• Chapter 7

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7.1 Ion Formation

• What is a chemical bond?
• The force that holds two atoms together.
• Bond formation
• attraction between the positive nucleus of one
  atom and the negative electrons of another atom
• attraction between positive and negative ions

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Ions

• Atoms or groups of atoms with a positive or
  negative charge
• Cation
• Positively charged ion
• Forms when an atom loses one or more valence
  electrons
• Metal ions
• Metals atoms are reactive because they lose
  valence electrons easily.
• Examples Magnesium to Mg2, Potassium to K1

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Ions

• Anion
• Negatively charged ion
• Forms when an atom gains one or more electrons
• Anions designated by the ending ide
• Nonmetal ions
• Gain the number of electrons that, when added to
  their valence electrons, equals 8
• Examples Phosphorus to Phosphide (P3-) ,
  Fluorine to Fluoride (F1-), Oxygen to Oxide (O2-)

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7.2 Ionic Bonds and Ionic Compounds

• Ionic bond
• Bond formed by electrostatic force holding
  oppositely charged particles together
• Ionic Compounds
• Compounds that contain ionic bonds
• Binary Ionic Compounds
• Contain a metallic cation and a nonmetallic anion
• Examples sodium chloride (NaCl), magnesium oxide
  (MgO)
• Overall charge of Compound must equal zero

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Ionic Compounds

• Examples
• Sodium and Nitrogen
• Lithium and Oxygen
• Strontium and Fluorine
• Aluminum and Sulfur

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Properties of Ionic Compounds

• Physical Structure
• Cations and Anions exist together in a ratio
  determined by the of electrons transferred
• Crystal lattice
• 3-dimensional geometric arrangement of particles
• Each cation is surrounded by anions and each
  anion is surrounded by cations
• Physical Properties
• Dependent upon how strongly the particles that
  make up the matter are attracted to one another
• Melting point, boiling point, hardness,
  conductivity

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7.3 Names and Formulas for Ionic Compounds

• Formula unit the chemical formula for an ionic
  compound which represents the simplest ratio of
  the ions involved.
• Monatomic ions one atom ions
• Examples Li1, Mg2, N3-, Te2-, F1-
• The superscripted number next to an ion is
  referred to as the oxidation number.

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Binary Ionic Compounds

• Bond between a cation and an anion.
• Cation written first followed by anion
• The ratio of ions must balance the oxidation
  numbers (no overall charge)
• Examples K1 and O2- create K2O
• Na1 and Cl1-
• Cs1 and N3-
• Al3 and Br1-

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Polyatomic Ions

• Ions made up of more than one atom.
• Pg. 221 Table 9
• Bond in the same manner as binary ionic compounds
• Examples
• Na1 and NO31-
• Ca2 and ClO31-
• Al3 and CO32-

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Naming Ionic Compounds

• Oxyanions polyatomic ion composed of an
  element, usually a nonmetal, bonded to one or
  more oxygen atoms.
• Chemical nomenclature
• Name the cation followed by the anion. (cation is
  always written first)
• For monatomic cations, use the element name.
• For monatomic anions, use the root of the element
  name plus the suffix ide.
• Example CsBr
• To distinguish between multiple oxidation numbers
  of the same element, the name of the chemical
  formula must indicate the oxidation number of the
  cation. The oxidation number is written as a
  Roman numeral in parentheses after the name of
  the cation.
• Example Fe2 and O2- ions form FeO,
  iron(II)oxide
• Fe3 and O2- ions form Fe2O3, iron(III)oxide
• When the compound contains a polyatomic ion,
  simply name the cation followed by the name of
  the polyatomic ion.
• Example NaOH
• (NH4)2S
• CaCl2

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7.4 Metallic Bonds and the Properties of Metals

• Metallic Bonds are formed by the attraction of a
  metallic cation for delocalized electrons.
• Electron sea model proposes that all the metal
  atoms in a metallic solid contribute their
  valence electrons to form a sea of electrons.
• Delocalized electrons electrons present in the
  outer energy levels of metallic bonds are not
  held by any specific atom and can move easily
  from one atom to the next.

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Properties of Metals

• Melting and boiling points
• In general, metals have moderately high melting
  points and high boiling points.
• Malleability, ductility, and durability
• Metals are malleable (hammered into sheets)
• Metals are ductile (drawn into wire)
• Metals are durable (strong attractions between
  cations and electrons)
• Thermal conductivity and electrical conductivity
• The movement of mobile electrons around positive
  metallic cations make metals good conductors.
• Hardness and strength
• D block electrons increase the hardness and
  strength

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Metal Alloys

• Alloy a mixture of elements that has metallic
  properties.
• Due to the unique blend of properties, alloy have
  a wide range of commercial applications.
• List of common commercial alloys pg. 228 Table 13
• Substitutional Alloy
• Some of the atoms in the original metallic solid
  are replaced by other metals of similar atomic
  size.
• Sterling silver
• Interstitial Alloy
• Formed when the small holes (interstices) in a
  metallic crystal are filled with smaller atoms.
• Carbon steel