Ch. 5.2 NotesIonic Bonding and Salts

Ionic Bonds Cations (+) lose 1 or more e- Anions (-) gain 1 or more e-

Receive/give e- from/to one another

Resulting + and – charges are attracted, form an ionic bond

Bond creates a compound

Example… NaCl – sodium chloride (table salt)

Ionic compound Na Na+ + e- Cl + e- Cl-

The e- lost by Na is gained by Cl Positive Na+ is attracted to negative Cl-

Energy changes Transferring electrons/forming compounds involves energy

changes Na + energy Na+ + e-

What is this energy called? Cl + e- Cl- + energy Overall formation of ionic compound (also called a salt)

releases energy

Energy changes Salt formation involves

endo- and exothermic steps

Overall reaction is exothermic Amount of energy

released when ionic bonds formed is called lattice energy

Ionic compounds Ratio of anions to cations always reflects a neutral charge

For every 1 Na+, there’s 1 Cl-

For every 1 Mg2+, there’s 1 O2-

For every 1 Ca2+, there are 2 Cl-

Ionic compounds Don’t consist of

molecules Form crystal lattice

Ex. NaCl – multiple ions bonded together, but still maintain the ration necessary for a neutral compound

Variations in ionic crystal lattices

Properties of Ionic Compounds Strong bonds High melting and boiling points Rarely gaseous at room temp. Hard Brittle – break along a cleavage

plane

Properties of Ionic Compounds Conduct electric current

(Typically) only when the ions can move around freely, aren’t locked into lattice

This happens if ionic compound is in liquid state or dissolved