Ionic Bonding

• Metal atoms with low ionization energies and non-metal atoms with high electron affinity form cations (+) and anions (-) • Oppositely charged ions attract to a crystalline structure

Lattice Energy

  Quantity of energy required for 1 mole of the solid ionic substance to be separated into its ions Higher – more stable  Very high in ionic substances  This accounts for high melting temp., and hard and brittle nature

Process of Ionic Bond Formation

 Always exothermic  Compound forms because it is more stable (lower in energy) than its elements  Stability comes from packing of ions together  Lattice energy increases as the charges on ions increase and radii decrease

Ionic Structures

 Can have many types of arrangements  Arrangement depends on the charge and size of the ions involved

• Which substance would have a higher lattice energy : NaF or MgO?

• Which would have a higher lattice energy: FeO or Fe 2 O 3 ?

Forming The Ions

 The ions are formed when electrons are transferred from the atom with low electronegativity to an atom with high electronegativity  Predict the compound formed between aluminum and fluorine.

Transition-Metal Ions

 Transition metals form many differently charged ions (some 2+, some 1+, some 3+)  In forming ions the transition metals lose the s electrons first and then as many d electrons as necessary to form the ion of that particular charge

Write the Configuration of Each

Co 2+ Co 3+ Cr 3+

Sizes of Ions

 Cations are smaller than their parents  Anions are larger than their parents  Ions of the same charge, size increases going down a group  List the following in order of decreasing size Mg 2+ , Ca 2+ , Ca

Isoelectric Series

 Comparitive sizes of ions all possessing the same number of electrons  As nuclear charge increases, the radius decreases  O 2 > F > Na + > Mg 2+ > Al 3+

Example

 Arrange the ions S 2 , Cl , K + , and Ca 2+ of decreasing size.

in order