1. Chapter 7 7-1

2. How are ions different from atoms? An ion is an atom that has gained or lost one or more electrons. An ion is like an atom, but the number of electrons does not equal the number of protons.

3. The following equation shows the formation of a sodium ion from a sodium atom. Na Na + + e -

4. Using the same name for both the atom and the ion indicates that the nucleus is unchanged. The ion still has same number of protons and neutrons, like the atom.

5. Changes in electron arrangements change chemical properties. Cations- ions with a positive charge.  They have more protons than electrons. Anions- ions with a negative charge.  They have more electrons than protons.

6. Collections of cations are never found without a similar number of anions nearby. This happens because the charges must be balanced. The concept of having equal numbers of opposite charges is called electroneutrality.

7. Many simple ions have a noble gas configuration. Atoms and ions with the same electron configuration are said to be isoelectronic with each other.

8. Transition metals form stable ions too. Not all simple ions are isoelectronic. Transitions metals, for example, are all cations.

10. Concept check How does an atom form a negative ion? How does an atom form a positive ion?

11. Names and Formulas for Ions Ions borrow their names from the names of elements. When an element forms two or more ions, the ions are distinguished by roman numerals to indicate charge. (transition metals only) Cu + copper (I) ion Cu 2+ copper (II) ion

12. An ionic compound composed of a simple cation and a simple anion is called a binary ionic compound. Common table salt Na + Cl -

13. Binary ionic compounds are easy to name. Bi- means two. In this case two elements. To name a simple anion, just add –ide to the end of the element name. Cl - is the chloride ion.

14. Naming binary compounds is simple. The name has two words:  The name of the cation (the positive ion) Followed by…  The name of the anion (the negative ion) Na + Cl - - sodium chloride

15. Writing Formulas The formulas must indicate the numbers of anions and cations. You must combine cations and anions in such a way that the negative charges equals the positive charges.

16. Subscripts are used to denote the number of ions represented in the compound. Example: Mg 3 N 2

17. How To: What is the formula for aluminum oxide? Symbol for aluminum cation : Al 3+ Symbol for oxide anion :O 2-

18. Step 1: Write the ions side by side. Step 2: Draw arrows that cross each other. Al 3+ O 2-

19. Step 3: Put the number of charges at the ends. Al 3+ O 2- 2 3

20. Step 4: Write the formula as follows: a.) write the positive ion without its charge Al b). Write the number as a subscript Al 2

21. c.) write the negative ion without its charge Al 2 O d.) write the number as a subscript Al 2 O 3 FINISHED!!