Ionic Bonding

Ionic Compound Composed of positive and negative ions that are attracted to each other  Cation  Anion  Must be the same number of electrons transferred (same number of positive and negative charges) Formula unit: simplest representation of the ions forming a compound  Chemical formula tells the ratio of ions forming the formula unit  Ratio of ions depends on the charges of the ions Example: Ca bonding with F (draw electron dots)

Characteristics of Ionic Compounds Ions arranged in a regular repeating pattern called a crystal lattice  This minimizes potential energy  Crystal lattice depends on attractive forces Cation to anion Nucleus for other atoms’ electrons  Crystal lattice depends on repulsive forces Like charged ions Electrons of one atom to electrons of another atom  Distances between ions is a balance of energy of attraction and repulsion

Calcium carbonate

Characteristics of Ionic Compounds Lattice energy: energy released when one mole of ionic compound formed from its gaseous components  Used to compare bond strengths of ionic compounds Ionic compound may contain polyatomic ions  Group of covalently bonded atoms with an overall charge Example: Carbonate (CO 3 ) -2 High melting and boiling points due to strong attraction Often brittle

Common Polyatomic Ions Ammonium NH 4 + Dimercury Hg 2 +2 Acetate CH 3 COO- Bromate BrO 3 - Chlorate ClO 3 - Chloride ClO 2 - Cyanide CN- Bicarbonate HCO 3 - Hydroxide OH- Nitrate NO 3 - Nitrite NO 2 - Permanganate MnO 4 - Carbonate CO 3 -2 Chromate CrO 4 -2 Dichromate Cr 2 O 7 -2 Sulfate SO 4 -2 Sulfite SO 3 -2 Phosphate PO 4 -3

Test your Knowledge: Draw the Lewis electron dot structure for the formation of ionic bonds between: Lithium and chlorine Calcium and iodine Sodium and fluorine