1. Bell Ringer 10-21-09 What does the period number tell you?
What does the group number tell you?
How many electrons can the 1st energy level hold?
How many electrons can the 2nd energy level hold?

2. Chapter 5 Section 2
Ionic Bonds

3. Electron Dot Diagrams
An electron dot diagram includes the symbol for the element surrounded by dots.
Each dot stands for one valence electron.

4. Ion An ion is an atom with an electric charge.
If an atom loses an e- it becomes positively charged.
If an atom gains an e- it becomes negatively charged.

5. Polyatomic ions Poly = many Polyatomic = “many atoms”
a group of atoms that reacts as a unit

6. Ionic bonds
Ionic bonds form because of the attraction between positive and negative ions.
A compound that consists of positive and negative ions = ionic compound

7. When atoms form ionic bonds, they transfer electrons.
Ionic Bonding
When atoms form ionic bonds, they transfer electrons.
Gaining electrons
Losing electrons

9. Chemical formula
Chemical formula is a combination of symbols that shows the ratio of elements in a compound.
Ex: H2SO4
CaCO3
2H2SO4
CH4
Ionic

10. A subscript is the number in the chemical formula that tells how many atoms are in a molecule.
If there is no subscript, the number 1 is understood to be there.

11. Naming ionic compounds
When you name an ionic compound, the name of the positive ion comes first, then the name of the negative ion comes last.

12. Properties of ionic compounds
In general, ionic compounds are hard, brittle crystals that have high melting points.
When dissolved in water or melted, they conduct electricity.

14. A crystal is an orderly, three dimensional pattern of ions or atoms in a solid.