2.6: polyatomic ions

polyatomic ions

• polyatomic ion: an ion that is composed of two or more atoms bonded together that act as a unit
• nonbinary compound (aka ternary compounds, tertiary compounds): a compound consisting of three or more elements
• the sum of a compound’s charges must still equal zero
• include polyatomic ions

three types of nonbinary ionic compounds

• one metal cation (positive charge +) and one polyatomic anion (negative charge -)
  • eg. NaOH
• one polyatomic cation (+) and one nonmetal anion (-)
  • eg. NH₄Cl
• one polyatomic cation (+) and one polyatomic anion (-)
  • eg. Nh₄OH

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naming nonbinary ionic compounds

1. write the name of the cation as it appears on the periodic table (metal cations) or as it appears on your reference source (polyatomic cations)
2. a free source if your teacher doesn’t provide one is this list
3. write the name of the anion as it appears on the periodic table (metal) or as it appears on your reference source (polyatomic)
4. when naming nonbinary ionic compounds, you do not need to change the ending of polyatomic ions
5. use roman numerals to indicate charge if the metal cation is multivalent

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