Dissociation & Ionization

Molecular Compounds: Consist of two non-metals that share electrons. They are neutrally charged compounds (example: H2O, O2, CO2).

Ionic Compounds: Consist of one metal and one non-metal or one metal and one polyatomic ion. They consist of positively charged and negatively charged ions (example: NaCl, CaCl2).

Acids: Are types of molecular compounds and that result in the formation of H+ ions and an anion when dissolved in water (example: HCl).

Bases: Are types of ionic or molecular compounds. Ionic bases result in an OH- ion and cation when dissolved in water (example: NaOH).

ionic compounds disperse electrically charged particles

this is due to water’s polarity and the charge on the ions

the positive ion is surrounded by the negative end of the water molecule

the negative ion is surrounded by the positive end of the water molecule

This causes the ions at the edges of the crystal formation to be tugged at and dislodged until all of them are surrounded by water (solvation).

DISSOCIATION =  the separation of ions that occurs when an ionic compound dissolves in water

This is why ionic compounds can conduct electricity so well in solution

shows the separation of ions in a chemical equation

H₂O is shown over top of the arrow because it is a solvent and is NOT used up or changed

aqueous states are used (as (aq) = dissolved in water)

Examples: (**still need to balance equation)

Stronger bond formation after dissociation/ionization results in exothermic reactions.

• Example: NaCl, The bond between hydrated ions (Na+ and Cl-) and water releases energy and since this energy released is higher than the energy required to break the ionic bond it is exothermic.

Weaker bond formation after dissociation/ionization results in endothermic reactions. 

• Example: NH4NO3 is an ionic compound. The breaking of intermolecular forces to form NH4+, NO3- ions requires a lot of energy (stronger electrostatic forces), thus energy is absorbed from the environment.

To determine whether something will be soluble in water (able to dissociate or ionize) use your solubility chart in your data booklet

These ones you need to know: