- Highly reactive metals like Na, K, and Al are extracted by electrolysis of their molten salts.
- Aluminium is extracted from bauxite using leaching and electrolysis.
- Cryolite and fluorspar help lower the melting point of alumina during extraction.
- Moderately reactive metals like Zn and Fe are extracted by roasting or calcination, then reduced with carbon or aluminium.
- Less reactive metals like gold and silver are found in the free state and extracted by heating.
Definitions [19]
Definition: Non-metals
Non-metals, except hydrogen, are the elements which form negative ions by the gain of electrons.
Definition: Metalloids or Semi-Metals
Certain elements which show properties of both metals and non metals are called metalloids or semi-metals.
Definition: Cation
A metallic atom, which loses electron(s), becomes a positively charged ion and is known as a cation.
Definition: Ion
An ion is a charged particle which is formed due to the gain or the loss of one or more electrons by an atom.
Definition: Anion
A non-metallic atom, which gains electron(s), becomes a negatively charged ion and is known as an anion.
Definition: Electropositive Element
A metallic element, whose one atom readily loses electron(s) to form a positively charged ion, is an electropositive element.
Definition: Electronegative Element
A non-metallic element, whose atom readily accepts electron(s) to form a negatively charged ion, is an electronegative element.
Definition: Electrovalent Bond
The cation and the anion being oppositely charged attract each other and form a chemical bond. Since this chemical bond formation is due to the electrostatic force of attraction between a cation and an anion, it is called an electrovalent (or an ionic) bond.
Definition: Electrovalent (or Ionic) Compounds
The chemical compounds formed as a result of the transfer of electrons from one atom of an element to one atom of another element are called ionic (or electrovalent) compounds.
Definition: Electrovalency
The number of electrons that an atom of an element loses or gains to form a electrovalent bond is called its electrovalency.
Define the following term.
Mineral
Most of the elements occur in nature as in combined state as minerals. The chemical composition of minerals is fixed.
Define calcination.
If an ore is a carbonate or a hydrated oxide, it is heated in the absence of air to a temperature that is high but insufficient to melt the ore. The process is known as calcination.
Define the following term.
Gangue
The impurities (sand, silt, soil, gravel, etc.) present in the ore are called gangue.
Define roasting.
Roasting is the process of heating concentrated ore to a high temperature in the presence of air. The process is usually carried out for sulphide ores.
Define the term:
Slag
The product obtained by the combination of gangue with flux is called slag.
Define the term:
Flux
The substance added to get rid of gangue in the extraction of metal is called flux.
Define the Ore.
Minerals from which metals can be extracted profitably are known as ores.
If minerals contain a very high percentage of a particular metal and the metal can be profitably extracted from it. These minerals are called ores.
Definition: Refining
Refining is the process by which crude metal is purified.
Definition: Corrosion
Corrosion is the gradual damage of metals caused by their reaction with components of the atmosphere, such as oxygen and moisture.
Key Points
Key Points: Physical Properties of Non-metal
- Most metals are solids at room temperature, but mercury is a liquid, and gallium and caesium melt in the palm of the hand due to their very low melting points.
- Alkali metals (lithium, sodium, potassium) are soft, low-density metals with low melting points, unlike most metals.
- Iodine, though a non-metal, shows a metallic lustre, which is unusual for a non-metal.
- Carbon exists in allotropes: diamond is the hardest natural substance, and graphite is a good conductor of electricity.
- Nonmetals are usually non-lustrous, soft, poor conductors, and exist in solid or gas states, with bromine being the only liquid non-metal.
Key Points: Extraction of Metals
Key Points: Refining of Metals
- Refining means purifying a crude metal by removing impurities.
- Distillation is used for metals such as zinc and mercury, which have low boiling points.
- Liquation is used for soft metals such as lead and tin, which have low melting points.
- Electrorefining uses electricity to purify metals like copper and silver.
- Pure metal collects at the cathode; impurities settle as anode mud.
Important Questions [18]
- Name the following: Main ore of aluminium.
- In the Extraction of Aluminium: Name the Process of Concentration of Bauxite.
- In the Extraction of Aluminium Write the Cathode Reaction in Electrolytic Reduction of Alumina.
- In the Extraction of Aluminium: Write the Function and Formula of Cryolite in the Extraction of Aluminium.
- In the Extraction of Aluminium: Draw the Diagram for the Extraction of Aluminium.
- In the Extraction of Aluminium: Why is It Necessary to Replace Anodes Time to Time?
- Draw a Well-labelled Diagram of Extraction of Aluminium. Write the Anode Reaction in Electrolytic Reduction of Alumina.
- Name One Metal Each Occurring as : an Oxide
- Name One Metal Each Occurring as : a Sulphine
- Name One Metal Each Occurring as : a Carbonate
- Give Two Examples of Alloys with Their Chemical Composition.
- Tinning : Tin : : Galvanizing :
- Write two methods of preventing the rusting of iron.
- Choose the Correct Alternative and Rewrite the Following: Iron is _____________________
- What is Anodising? Give Its Applications.
- Answer the following question. What are alloys?
- Write Three Methods of Preventing Rusting of Iron.
- What is an alloy?
