S10 3: Classifying Compounds, Ionic

• 3 main types of compounds:

  • Ionic compounds: usually metal-nonmetal combinations, more accurately, cation-anion combination
  • Molecular compounds: nonmetal-nonmetal combinations
  • Alloys and intermetallic compounds: metal-metal combinations and solutions
• Properties of Ionic Compounds:

  • High melting point solid at SATP
  • Solubility in water depends on the ions
  • Solutions are conductive
• Properties of Molecular Compounds:

  • Solid, liquid, or gas at SATP
  • Generally lower melting points than ionic compounds
  • Electrically neutral molecules
  • Solutions are not conductive
• Acids:

  • Solids, liquids, or gases that form conducting aqueous solutions that make blue litmus paper turn red and have a pH below 7
  • Only show properties when dissolved in water
  • Usually distinguished by starting with H or ending in COOH
• Bases:

  • Compounds that form aqueous solutions that turn red litmus paper blue
  • Usually distinguished by ending in OH
• Neutral compounds:

  • Form aqueous solutions that do not affect litmus paper
• Writing Simple Ionic Formulas:

  • Write down the symbol for the cation and determine the charge separately
  • Write down the symbol for the anion and determine the charge separately
  • Ensure the charge is zero by balancing the number of cations and anions
  • Use the metal's most common ion charge for transition metals unless otherwise specified
• Naming Simple Ionic Compounds:

  • Name the cation (metal) as it appears on the periodic table
  • Name the anion (nonmetal) by dropping the ending and adding "ide" in lowercase letters
  • Charge for transition metals is denoted by roman numerals in brackets after the metal
  • polyatomic ions = single ions
• Nomenclature for Ionic Hydrates:

  • Name the ionic compound as usual and add the number of water molecules to the name
  • Indicate the number of water molecules attached to the ionic compound using prefixes or numbers
• Ionic Hydrates:

  • Water is loosely bonded with an ionic compound
  • When hydrates are heated, the bond to water is broken, releasing water vapor to the atmosphere