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 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+ in order of decreasing size.