6.4 Polyatomic Ions

6.4 Polyatomic Ions

  • Write the name and formula for the compound.
  • Nonmetals such as sulfur, carbon, and nitrogen are covalently bonds to oxygen atoms.
  • The charges of the polyatomic ion are 1-, 2-, or 3-.
    • NH + 4 is the only polyatomic ion with a positive charge.
  • There are groups of atoms that have an ionic charge in many products.
  • There is a 3- charge forphosphate and phosphite.
  • Four different polyatomic ion with oxygen are formed by the halogens.
  • You can identify polyatomic ion in the name of a compound with the help of the prefixes and endings.
    • There are exceptions to this naming pattern, such as the hydroxide ion and cyanide ion.
  • The most common polyatomic ion for that element is indicated by the formulas and names in bold type.
  • A polyatomic ion is associated with a different charge.
    • One of the electrical attraction is the bonding between polyatomic ion and other ion.
    • The compound sodium chlorite consists of both Na+) and chlorite ion held together by ionic bonds.
  • We follow the same rules of charge balance as we did for writing the formulas for simple ionic compounds.
    • Zero is the total negative and positive charges.
    • For example, consider the formula for a compound with both chlorite and sodium chlorite.
  • When more than one polyatomic ion is needed for charge balance, parentheses are used.
    • The number needed for charge balance is indicated by a subscript in the polyatomic ion.
    • Consider the formula for magnesium nitrate.
    • The magnesium and nitrate ion are in this compound.
  • Two nitrate ion are needed to balance the magnesium ion.
  • Amphojel is an antacid that contains aluminum hydroxide.
  • Define the cation and polyatomic ion.
  • The charge is balanced by three OH- ion.
  • Use the subscripts from charge balance to write the formula.
  • The formula for the compound is written in parentheses and outside the right parenthesis.
  • Write the formula for the compound.
  • We first write the positive ion, usually a metal, and then we write the name for the polyatomic ion.
    • You need to learn to recognize the polyatomic ion in the formula and name it correctly.
    • No prefixes are used with other ionic compounds.
  • The formulas and names of some ionic compounds are listed in TABLe 6.9.