Chemical Names of Ionic Compounds by h378WqK

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									Chemical Names of Ionic
     Compounds
        Lesson 7
 What are Ionic Compounds?
• Ionic compounds are made up of positive and
  negative ions.
  – All of the positive and negative ions for a pattern
     • Negative and positive ions attract.
     • Negative and negative and positive and positive repel.
  – Ionic compounds form solid crystals.
  – Ionic compounds are like a solid stack of bricks.
Where does our salt come from?
        Naming Ionic Compounds
                Formula for naming ionic compounds
                  positive ion + negative ion + -ide.
  If a compounds contains 2 elements the first is ALWAYS a metal
  If a compounds contains 2 elements the second is ALWAYS a non-metal


For example: magnesium (metal) and oxygen (non-metal).

STEP 1: The positive ion is the first part of the name
STEP 2: The negative ion forms part of the ending of the name
STEP 3: Add -ide to the end of the name


     magnesium oxygen -ide                   Magnesium oxide
              Try these
                                  P 186-187 text




• Calcium and Bromine
                         Calcium bromide

• Lithium and Nitrogen

                         Lithium nitride

• Zinc and Sulfur
                         Zinc sulfide
        Writing formulas for
         Ionic Compounds
• Ionic formulas are based on the ions of the
  atoms involved
        Example: What is the name of Ca3N2?

          Ca is the positive ion and is calcium.

          N is the negative ion and is nitrogen.

          Drop the ending of the negative ion,
          nitrogen and add -ide.

          Calcium nitride
      Writing formulas for
   Ionic Compounds continued
Rules for writing formulas of ionic compounds
– In an ionic compound, the positive charges
  balance out the negative charges.

– The ratio of positive to negative charges gives
  the proper formula.

– The ratio is always written in reduced form.
     Example: Hydrogen chloride
• Identify each ion and its charge
• Determine the total charges needed to balance
  positive and negative
• Note the ratio of positive ions to negative ions
• Use subscripts to write the formula, 1’s are not
  shown in subscript

 ions                          H +   and       Cl -

Total charge to balance              +1 = -1
 ratio                                 1:1
formula                                HCl
 Example: Potassium and Sulfur


ions                      K +   and   S 2-

Total charge to balance     +1+1 = -2
ratio                           2:1
formula                         K2S
Example: Aluminum and Sulfur

ions                      Al3+ and S2-
Total charge to balance    +3+3 = -2-2-2
ratio                         2:3
formula                       Al2S
                              3
Formulas are always written in their
       most reduced form

 ions                         Ca2+   and   O 2-

 Total charge to balance        +2 = -2
 ratio                           1:1
 formula                         Ca2O2
 Simplify and write in most          CaO
 reduced form
              Name of a compound=words
              (element names spelled out)

              Formula of a compound=symbols
              (element symbols and subscripts)


                        Homework
To help you practice naming ionic compounds and writing ionic formulas

   • Workbook,          p62            #1-3
   • Text book,         p187           #1 a,c,e,g,h,i

								
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