Ionic Bonding and Ionic Compounds I can classify a bond as ionic and describe the characteristics including bond length, bond energy, and lattice structure

What is the characteristics of an ionic bond and how do they compare to covalent bonds?  I can Define Ionic and covalent bonds Define Ionic and covalent bonds List the properties that characterize the type of bonds List the properties that characterize the type of bonds Predict the characteristics and properties of a compound based on the type of bond. Predict the characteristics and properties of a compound based on the type of bond.

Ionic compounds  Metal plus nonmetal  Cation plus anion  + ion plus – ion  Remember that the positive charge must cancel the negative charge

Formula Units  Simplest collection of atom from which an ionic compound’s formula can be established.  Remember that the overall charge on a ionic compound is neutral.

Examples  Na + -- Cl NaCl  Notice that the charges are cancelled out.  The name is sodium chloride  Ca +2 F CaF 2  Notice that the charges cancel out because 2 F and 1 Ca.  Ca +2 F - F -

Two ways to create Formula Units  1. Add ions until the charges cancel  2. Criss-Cross method Ca +2 F - Ca +2 F - Ca 1 F 2 Ca 1 F 2

Practice  Li and F  Na and Br  Ca and I

Lewis structures  Draw the lewis structure for Li  Draw the lewis structure for F  Show the transfer of electrons

Ionic Characteristics  Ionic compounds will often form crystal lattice structures. Purple is Sodium Na Green is Cl

Ionic Characteristics  Bond Strength in ionic compounds, amount of energy released when separated ions in a gas come together to form a crystalline solid.  Lattice energy is the energy released when one mole of an ionic crystalline compound is formed from gaseous ions.  Strong bonds, Increased melting/boiling point (Do not vaporize as readily as covalent)

Ionic bonds are strong and have the following properties  High melting and boiling points  Hard  Brittle  In a molten state, or when dissolved in water ionic compounds are electrical conductors, because the ions can move freely to carry the electrical charge.  (solid state- no movement- no electrical conductivity)  Dissolved in water – electrical conductors.

Why are ionic compounds hard but brittle?  In an ionic crystal, even a slight sift of one row of ions relative to another causes a large build up of repulsive forces. These forces make it difficult for one layer to move relative to another, causing ionic compounds to be hard. If one layer is moved, however the repulsive forces make the layer part completely, causing ionic compounds to be brittle.

Strong but brittle

Polyatomic Ions  Atoms that are covalently bonded to each other to form a group of atoms that has both molecular and ionic characteristics.  The charge on the polyatomic ion results from an excess of electrons, or shortage.  Polyatomic (-) plus a metal  Polyatomic (NH 4 + ) plus a nonmetal

METALLIC BONDING  How does metallic bonding compare to covalent and ionic. Characteristics of metallic bonds Characteristics of metallic bonds Predict properties based on the bond type Predict properties based on the bond type

Metallic bonds  Chemical bonding that results from the attraction between metal atoms and surrounding sea of electrons  Sea of electrons is due to the fact that there are overlapping empty orbital and the delocalized electrons can move freely throughout the entire metal.  Electrically charged

Metallic Bonding

What are the properties of metals?  Why do they have these properties

Metallic Properties  High electrical conductor  High thermal conductor (free e-)  Absorb a wide range of light frequencies because of the small energy differences between orbital's. – makes them shinny  Malleability – ability of a substance to be hammered into a thin sheet  Ductility – ability of a substance to be drawn into a wire. This is possible because the metallic bonding is th same in all directions throughout the solid. One plane can slide past the other plane without encountering any; resistance or breaking any bonds. This is possible because the metallic bonding is th same in all directions throughout the solid. One plane can slide past the other plane without encountering any; resistance or breaking any bonds.

Metallic Bond Strength  Metallic bond strength varies with the nuclear charge of the metal atoms and the number of electrons in the metal’s electron sea.  Reflected in the heat of Vaporization. When a metal is vaporized, the bonded atoms in the normal (usually solid) state are converted to individual metal atoms in the gaseous state.

Metallic Bonding Heat of vaporization  Page 182, table 6-4