1. Ionic Compounds Names and Formulas

2. Vocabulary Ion – an atom that has an electrical charge due to the gain or loss of electrons Monatomic – contains one (1) atom Polyatomic – contains 2 or more atoms Oxidation number – the charge on a monatomic atom

3. Positive Ions Positive ions form when electrons are lost Groups 1A, 2A, 3A, and the transition metals form positive ions. Oxidation numbers:  Group 1A is 1+  Group 2A is 2+  Group 3A is 3+

4. Negative Ions Negative ions form when electrons are gained. Groups 5A, 6A, and 7A form negative ions. Oxidation numbers:  Group 5A is 3-  Group 6A is 2-  Group 7A is 1-

5. More vocabulary Ionic Bond – The electrostatic force that holds oppositely charged particles together. Ionic Compound – a chemical compound formed by an ionic bond. Salt – a name for an ionic compound.

6. Properties of Salts 1. very hard – 2. high melting points – 3. brittle – each ion is bonded to several oppositely -charged ions many bonds must be broken with sufficient force, like atoms are brought next to each other and repel calcite

7. Naming Binary Ionic Compounds 1 st ion is the positive ion Use the element name 2 nd ion is the negative ion Take the element name, but change the ending to –ide. Examples: chlorine becomes ____________ sulfur becomes _____________

8. Naming Examples NaF MgCl 2 Al 2 O 3

9. Writing the Formula for a Binary Ionic Compound 1. Write the symbols for the ions. Include the oxidation numbers (charges). 2. Criss-cross the charges. The charge of one ion will become the subscript on the opposite ion. 3. Reduce the subscripts to a lowest-terms ratio. Note: the formula for an ionic compound gives the number of atoms in one formula unit.

10. Formula Examples aluminum chloride magnesium oxide

11. Polyatomic Ions Polyatomic ions are charged particles that have 2 or more atoms covalently bonded. A covalent bond is a chemical bond formed by the sharing of electrons. Polyatomic ions should be treated as a single unit. Example: SO 4 2- is the sulfate ion.

12. Naming Ionic Compounds containing Polyatomic Ions Cation – positive ion Anion – negative ion The cation: If it is a polyatomic ion, use the name of the ion as the first word. If it is a monatomic ion, use the element name.

13. The anion: If polyatomic, use the ion name as the second word. If monatomic, use the element name modified with the ending –ide. Examples: NH 4 Cl CaSO 4

14. Writing Formulas for Ionic Compounds with Polyatomic Ions Use the criss-cross technique that is used for the binary compounds. If the polyatomic ion needs a subscript, then place parentheses around the polyatomic ion. The subscript goes outside of the parentheses.

15. Examples sodium sulfate ammonium phosphate Iron (III) nitrate