• Disodium phosphate
• Sodium chloride
1. Guess the chemical formula for these compounds
2. Are they the same type of compound?
3. Are there any similarities or differences in the names of these compounds?
Cations
• Positively charged ions. – Always followed by the word ion or cation.
• Ex. Sodium ion or Sodium cation• Calcium ion• Aluminum ion
Anions
• These are negative charged ions.– Naming starts with the stem of the element
and then ends in an –ide. • Ex. Sulfide ion or Chloride ion or nitride ion
• Sulf -ide
Binary Compounds
• A compound composed of two elements.– Ionic compound is metal + nonmetal
– Ex. Potassium chloride • K+ and a Cl- Chemical formula of KCl
– Calcium bromide • Ca2+ and Br- Chemical formula is CaBr2
Naming Transition Metals
• D-block elements
• Form more than one ion with different charges
• Place Roman numeral in parentheses after the name of the element to indicate charge.
– Ex: Fe name: Iron (II)
Fe name: Iron (III)
+2
+3
What’s wrong with these names?
• K2O Potassium (II) Oxide » No (II) needed » Oxide should be lower case (oxide)
• CaCl2 Calcium dichlorine » Do not need prefix» chlorine should be chloride
Naming Polyatomic Ions
• Name cation + name of anion– Ex: Ca(CO3) = Calcium carbonate
• If there are two or more of a polyatomic ion, use a prefix.– Ex: Zn3(PO4)2 = Zinc diphosphate
Practice
• LiOH
• Mg(H30)2
Which part of the compound is a polyatomic ion?
Group of nonmetals following a metal= polyatomic ion
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