• 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

Ionic Bonding

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 Fe2O3?

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

Co2+

Co3+

Cr3+

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

Mg2+, Ca2+, Ca

Isoelectric Series

Comparitive sizes of ions all possessing the same number of electrons

As nuclear charge increases, the radius decreases

O2- > F- > Na+ > Mg2+ > Al3+

Example

Arrange the ions S2- , Cl-, K+, and Ca2+ in order of decreasing size.