Ionic Bonding

Formation of Bond Electrons are transferred from an atom of low electronegativity to one of high electronegativity Anion (-) and cation (+) formed Opposite charges attract – called an electrostatic force

Formula Unit Simplest ratio of atoms in an ionic compound Charges combine to form a net of zero Formulas are not molecules: they do not show exact numbers of atoms just ratios Another term for an ionic compound is salt

Example Show how the bond forms in each pair and tell the formula unit Ca and F K and O Al and O

Ions Arrangement Opposite ions arrange themselves with each positive ion surrounded by negative ions and each negative surrounded by positive ions Where potential energy is lowest This arrangement is called a crystal lattice

Lattice Energy Energy released when one mole of an ionic compound is formed from its ions Values will always be negative, because energy is released The larger the negative value for the lattice energy, the stronger the ionic bond in the crystal is

Lattice energy Compound (kJ/mol) NaCl −787.5 NaBr −751.4 CaF 2 − CaO −3385 LiCl −861.3 LiF −1032 MgO −3760 KCl −715

The notation for sodium chloride, NaCl, stands for one. A) Formula unit B) Molecule C) Crystal D) Atom

In a crystal of an ionic compound, each cation is surrounded by a number of. A) Molecules B) Positive ions C) Dipoles D) Negative ions

Compared with the neutral atoms involved in the formation of an ionic compound, the crystal lattice that results is. A) Higher in potential energy B) Lower in potential energy C) Equal in potential energy D) Unstable

The lattice energy of compound A is greater than that of compound B. What can be concluded from this fact? A) Compound A is not an ionic compound B) It will be more difficult to break the bonds in compound A than in compound B C) Compound B is probably a gas D) Compound A has larger crystals than compound B

The forces of attraction between molecules in a molecular compound are. A) Stronger than the attractive forces in ionic bonding B) Weaker than the attractive forces in ionic bonding C) Approximately equal to the attractive forces in ionic bonding D) Equal to zero

What type of force holds atoms together in an ionic bond? A) Van der Waals B) Dipole-dipole C) Electrostatic D) Hydrogen bonding

What type of bonding holds a polyatomic ion together? A) Ionic B) Metallic C) Covalent D) Hydrogen Bonding

Using the table below, which substance is held together by the strongest ionic bond? A) NaCl B) CaO C) KCl D) MgO E) LiCl