Ionic Compounds

LG: I can write formulas and draw Lewis structures for ionic compounds

Chemical Compounds

• A compound is a group of two or more atoms/ions held together by chemical bonds– Compounds can be ionic or molecular

• A chemical bond is the force holding two atoms or ions together in a compound (“invisible glue”)– Chemical bonds can be ionic or covalent

Formation of Ionic Compounds• An ionic compound forms when a nonmetal

removes an electron from a metal. – The resulting ions have opposite charge and are

attracted to each other– This electrostatic attraction is an ionic bond

Structure of Ionic Compounds• Ionic compounds do not exist in

the simplest ratio of ions; they form large arrangements called crystal lattice structures

• Crystals of different ionic compounds have different 3-D shapes

• The smallest repeating unit is called a formula unit

Properties of Ionic Compounds • Hard & have high melting and boiling

points– Each +ve ion is attracted to many –ve

ions (& vice versa); bonds resist being stretched

• Brittle– A sudden force offsets the lattice

structure and causes ions with the same charge to come into contact and repel

• Ionic compound are soluble in water and form electrolytes– Ions separate from one another and

can carry electric charge

Using Lewis Structures to Represent Ionic Bonds

• Lewis Dot Diagrams for atoms:– ie.

• Lewis Dot diagrams for ions: – ie.

• Lewis structures for ionic compounds:– Ie.

• The lowest ratio of ions that produces a neutral compound is the chemical formula: NaCl

Practice: Lewis Structures• Draw Lewis diagrams for the following atoms:

Mg Li F O N K Ca S

• Draw Lewis for each element above as an ion:

• Draw Lewis structures for the following ionic compounds:Lithium Fluoride Magnesium FluoridePotassium Oxide Calcium SulfideLithium Nitride Magnesium Nitride

• Write chemical formulas for each compounds above:

Homework

• New Book: Pg. 60 # 1 – 5, 7, 8• Old Book: Pg. 71 # 1 – 5, Pg. 73 # 9, Pg. 74 # 11