Presentation on theme: "Writing formulas for Ionic Compounds. Review Ionic compounds are composed of cations (metals) and anions (nonmetals). Although they are composed of ions,"— Presentation transcript:
Review Ionic compounds are composed of cations (metals) and anions (nonmetals). Although they are composed of ions, ionic compounds are electrically neutral. The positive charge equals the negative. The positive charge and the negative charge attract one another. This is how the bond is formed.
Writing Binary Ionic Formulas The cation (Metal) with the correct oxidation number is written first The anion (nonmetal) with the correct oxidation number is written second
Binary Ionic Formulas Criss– cross the charges from superscripts to subscripts using only their absolute value
Step 2: Criss-cross the superscripts to subscripts using only the absolute value Ba +2 Cl -1 BaCl 2 Why is there no subscript for Ba?
Step 3: Make sure all subscripts are in the lowest possible ratio. BaCl 2 If there are in the lowest possible ratio you are done!!
Writing Formulas for Ternary Ionic Compounds (3+ Elements) Formulas of Ionic compounds Containing Polyatomic Ions- it is imperative that you know the correct charges on these ions!!!!! When using multiple polyatomics, you must “keep it together” by putting it in parenthesis. Example: Ca 3 (PO 4 ) 2 - calcium phosphate The charge must still equal zero!