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

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

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

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

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

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

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

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

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

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

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

Chapter 5 Section 2 Homework – pg 188

1A. What is an ion?

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.

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.

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

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

2C. Write the formula for calcium chloride.

3A. List three properties of ionic compounds

3B. SKIP!