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Naming Compounds That Contain Polyatomic Ions. (NH 4 ) 2 Cr 2 O 7. How do we name this compound? This looks confusing!!. (NH 4 ) 2 Cr 2 O 7. Is it nitrogen tetrahydride dichro…….? NO. There is a much easier way of naming this compound.
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(NH4)2Cr2O7 • How do we name this compound? • This looks confusing!!
(NH4)2Cr2O7 • Is it nitrogen tetrahydride dichro…….? • NO. • There is a much easier way of naming this compound. • We can use our table of complex ions found on our periodic table!
(NH4)2Cr2O7 • NH4+ is ammonium • Cr2O72- is dichromate • The name of the compound is ammonium dichromate.
Naming Compounds With Complex Ions 1st step – Does the compound have more than 2 different elements? 2nd step – Is there a METAL involved? If you have answered yes to the previous questions, we are dealing with a complex ion. NOTE: After you have practiced naming compounds with complex ions, you will be able to recognize them easily.
Naming Compounds With Complex Ions • Naming these compounds is very similar to naming binary compounds. • 1 – You name the cation first. • 2 – You name the anion second. • Notice – the ending is usually “ate” or “ite” … only two are “ide”
Remember • Name the anion / polyatomic ion using its full name as found on the periodic table or complex ions chart. • When the compound contains a metal that has more then one possible cation (ie. Cu, Fe), use the Stock or Classical system.
Practice Makes Perfect • Na2SO4 • K3PO4 • Fe(NO3)3
Solutions • sodium sulfate • potassium phosphate • Iron (iii) nitrate
Practice Makes Perfect • sodium carbonate • cesium perchlorate • copper (ii) acetate • NOTE: most complex ions end in “ate” or “ite”; two common exceptions are hydroxide (OH-) and cyanide (CN-)
Solutions • Na2CO3 • CsClO4 • Cu(CH3COO)2 • You must put brackets around a complex ion if you are multiplying it by a subscript!