Properties of Ionic and Covalent Compounds Learning Intentions: I know the type of element present in ionic and covalent compounds I can carry out an experiment to determine the conductivity of ionic and covalent compounds. I know why there are differencies in mp and bp with ionic compounds, covalent molecules and covalent networks Success Criteria: I can state the properties of covalent and ionic compounds in terms of: MP and BP Conductivity Solubility Elements present

Properties of Ionic and Covalent Compounds Ionic Compounds - contain a metal and non- metal. - soluble in water but are insoluble in other covalent liquids (hexane and white spirit).

Water, hexane and white spirit all have covalent bonding. Water is an unusual covalent liquid as it is a good solvent for ionic substances. Most covalent liquids are good solvents for covalent substances.

Ionic Compounds Most ionic compounds dissolve easily in water, when they do the lattice breaks up to form free ions. The solutions formed will conduct electricity since there are charged particles (ions) which are free to move.

Melting ionic compounds also allows them to conduct by freeing their ions to move. Ionic compounds have high melting points due to the vast number of strong ionic bonds which must be broken - needs a lot of energy.

Covalent Compounds - contains only non-metal elements. - insoluble in water but are soluble in other covalent liquids (hexane and white spirit).

Covalent Molecule A molecule is two or more atoms joined together by covalent bonds. They have weak intermolecular forces between molecules. Example: water, oxygen or carbon dioxide

Weak bonds broken during heating

Can be a gas, liquid or solid at room temp. Never conduct Low mp and bp Can be a gas, liquid or solid at room temp. Never conduct Methane Covalent molecule

Covalent Network A network contains many strong covalent bonds. Example: Diamond, Graphite

Solid at room temperature They never conduct Very high mp and bp Solid at room temperature They never conduct The only exception to this rule is Graphite

Melting and Boiling Point Metals: high mp and bp, solids at room temp. Mercury is the only exception. Ionic substances: high mp and bp, solids at room temp. Covalent molecules: low mp and bp, can be solids, liquids or gases at room temp. Covalent network: high mp and bp, solids at room temp.

Experiment 1: Conductivity of Compounds The conductivity of different compounds were tested.

Substance State Conducts (Y/N) Ionic/ Covalent

c c i c c i i i i except graphite i i (s) (l) (aq) BONDING AND PROPERTIES SUMMARY Conductivity c = conductor, i = insulator Solubility in: Type of Bonding Other covalent liquids Melting Point Boiling Point (s) (l) (aq) Water Do not form solutions c c metallic insoluble insoluble high high i c c ionic soluble insoluble high high i i Covalent molecule i insoluble soluble low low Covalent network i except graphite i i insoluble soluble high high

Substance Low mp and bp High mp and bp Covalent Molecular Conducts electricity Only when molten or in solution Never Ionic Covalent Network