Daily HW (NC10):

“Anodization is a chemical process of forming a thick outer layer of oxide on metals like Aluminium to protect them from further oxidation.”

This is done by Electrolysis of Sulphuric Acid with Aluminium as Anode and Graphite as Cathode.

“Metals are Lustruous.”, by this we mean that metals are shiny.

“Metals are Sonorous.”, by this we mean that metals create sound when striked.

“Metals are Ductile.”, by this we mean that metals can be drawn into thin wires.

“Metals are Malleable.”, by this we mean that metals can be beaten into thin sheets.

The chemical properties of metals are,

1. Metals react with oxygen to form metallic oxides.
2. Metals generally react with water to form metallic hydroxides (bases).
3. Metals generally displace hydrogen gas from dilute acids.
4. Metallic Oxides are generally basic.
5. Metallic Oxides can be Amphoteric Oxide.
6. Metallic Oxides are Ionic Compounds.

Some metallic oxides can react with both base and acid, such metal-oxides are called Amphoteric Oxides.
Example: ZnO, AlCl₃

Properties of Ionic compounds are: They are solid and mostly brittle. Have high melting and boiling points. More energy is required to overcome the strong inter-ionic force of attraction. Generally soluble in water, but insoluble in inorganic solvents like kerosene, petrol,etc. Conduct electricity in aqueous solutions and in molten state as free ions can conduct electricity.

The substances which are present in the earth's crust and contain compounds of metals are called as Minerals.

The minerals from which metals can be economically extracted are called as Ores.

The impurities like stones, sand and dust which are present in the minerals and ores of a metal are together known as Gangue.