1. Section 2 – pg 184 Ionic Bonds
Chapter 5
Section 2 – pg 184
Ionic Bonds

2. Pg 184
Ions
Atoms with 5, 6, or 7 valence electrons become more stable when this # increases to 8
Atoms with 1, 2, or 3 valence electrons lose electrons to become more stable
When these two types of atoms combine (bond) electrons transfer from one to the other making both atoms more stable

3. Pg 185
How Ions Form
Ion: an atom or group of atoms that has an electric charge
If a atom loses an electron (losing a negative charge), the atom become a positive ion
If a atom gains an electron (gaining a negative charge), the atom becomes a negative ion

4. Pg 185
Polyatomic Ions
Polyatomic Ions: ions that are made of more than one atom
Polyatomic Ions react as a unit and have an overall positive or negative charge

5. Pg 186
Ionic Bonds
Ionic Bonds: the attraction between two oppositely charged ions
Ionic bonds form as a result of the attraction between positive and negative ions
Ionic Compound: a compound that consists of positive and negative ions

6. Chemical Formulas and Names
Pg 187
Chemical Formulas and Names
Compounds can be represented by chemical formulas
Chemical Formula: a combination of symbols that shows the ratio of elements in a compound
IE: Magnesium Chloride – MgCl2
Meaning - 1 magnesium and 2 chlorine

7. Formulas of Ionic Compounds
Pg 187
Formulas of Ionic Compounds
When ionic compounds form, the ions come together in a way that balances out the charges on the ions. The chemical formula for the compound reflects this balance.
Subscript: the ration of elements in the compound
If there is no subscript, then it’s a 1
Subscript of 2 means there are two Hs
No subscript means there is one O

8. Naming Ionic Compounds
Pg 187
Naming Ionic Compounds
For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion
The positive ion is usually a metal
If the negative ion is single, the name ends in –ide
Sodium Cloride – NaCl
If the negative ion is polyatomic, the name ends in –ate or –ite
Ammonium Nitrate – NH4NO3

9. Properties of Ionic Compounds
Pg 188
Properties of Ionic Compounds
In general, ionic compounds are hard, brittle solids with high melting points. When melted or dissolved in water, they conduct electric current

10. Pg 188
Ionic Crystal
Ionic compounds form solids by building up repeating patterns of ions
Attracted in an alternating pattern forming an orderly, three-dimensional arrangement called a crystal
Every ion is attracted to ions of opposite charge that surround it

11. Electrical Conductivity
Pg 188
Electrical Conductivity
Electric current: the flow of charged particles
When dissolved in water: the bonds between ions are broken allowing the ions to move freely -> conducts electricity
When melted the bonds are broken so it can conduct currents
As a solid, the ions are tightly bound and can’t move - > does not conduct current

12. Chapter 5 Section 2 Homework – pg 188

13. 1A. What is an ion?

14. 1B. Contrast sodium and chloride ions, including how they form
1B. Contrast sodium and chloride ions, including how they form. Write the symbol for each ion.

15. 1C. What holds the ions together in sodium chloride
1C. What holds the ions together in sodium chloride? Indicate the specific charges that are involved.

16. 2A. What information is given by the formula of an ionic compound?

17. 2B. The formula for sodium sulfide is Na2S
2B. The formula for sodium sulfide is Na2S. Explain what this formula means.

18. 2C. Write the formula for calcium chloride.

19. 3A. List three properties of ionic compounds

20. 3B. SKIP!