Metals and Non-Metals is one of the most important chapters in SSLC Science. In this chapter, students learn about the physical and chemical properties of metals and non-metals, reactivity series, corrosion, alloys, extraction of metals and ionic compounds. This article is prepared based on the uploaded LBA document.
Learning Points
This chapter mainly includes:
- Physical properties of metals and non-metals
- Chemical properties of metals
- Reaction of metals with air, water and acids
- Reactivity series
- Ionic compounds
- Alloys and their uses
- Extraction of metals
- Corrosion and prevention methods
What are Metals?
Metals are substances that are generally hard, shiny and good conductors of heat and electricity.
Physical Properties of Metals
- Metals are lustrous
- Metals are malleable
- Metals are ductile
- Metals conduct heat and electricity
- Metals produce sound when struck
The document asks questions related to ductility, malleability and conductivity.
Important Properties of Metals
Malleability
The property by which metals can be beaten into thin sheets is called malleability.
Ductility
The property by which metals can be drawn into wires is called ductility.
Sonorous Nature
Metals produce sound when struck.
What are Non-Metals?
Non-metals are substances that are generally soft and poor conductors of heat and electricity.
Properties of Non-Metals
- Non-metals are not lustrous
- They are brittle
- They are poor conductors of heat and electricity
- They are not sonorous
Graphite is a non-metal that conducts electricity.
Chemical Properties of Metals
1. Reaction with Oxygen
Metals react with oxygen to form metal oxides.
$\ce{2Mg + O2 -> 2MgO}$
Metal oxides are generally basic in nature.
2. Reaction with Water
Some metals react with water and produce hydrogen gas.
$\ce{Ca + 2H2O -> Ca(OH)2 + H2}$
Sodium and potassium react violently with cold water.
3. Reaction with Acids
Metals react with acids and release hydrogen gas.
$\ce{Zn + 2HCl -> ZnCl2 + H2}$
Hydrogen gas is usually released when metals react with dilute acids.
Displacement Reactions
A more reactive metal displaces a less reactive metal from its salt solution.
$\ce{Fe + CuSO4 -> FeSO4 + Cu}$
Iron is more reactive than copper, so it displaces copper from copper sulphate solution.
Reactivity Series
The arrangement of metals in decreasing order of reactivity is called the reactivity series.
Reactivity Order
K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au
Potassium is highly reactive, whereas gold is least reactive.
Ionic Compounds
Compounds formed by transfer of electrons are called ionic compounds.
Example
Formation of sodium chloride:
$\ce{Na -> Na^+ + e^-}$
$\ce{Cl + e^- -> Cl^-}$
Properties of Ionic Compounds
- High melting and boiling points
- Soluble in water
- Conduct electricity in molten state
- Hard and brittle
Alloys
An alloy is a homogeneous mixture of two or more metals or a metal and non-metal.
Examples of Alloys
- Brass → Copper + Zinc
- Bronze → Copper + Tin
- Solder → Lead + Tin
- Steel → Iron + Carbon
Alloys are harder and stronger than pure metals.
Corrosion
The slow destruction of metals due to reaction with air and moisture is called corrosion.
Rusting of Iron
Rusting occurs when iron reacts with oxygen and moisture.
$\ce{4Fe + 3O2 + xH2O -> 2Fe2O3 . xH2O}$
Prevention of Rusting
- Painting
- Applying grease or oil
- Galvanization
- Alloying
Galvanization means coating iron with zinc to prevent rusting.
Metallurgy
The process of extracting metals from ores is called metallurgy.
Important Processes
Calcination
Heating carbonate ores in absence of air.
Roasting
Heating sulphide ores in the presence of air.
Reduction
Removing oxygen from metal oxide to obtain metal.
Thermite Reaction
The reaction between iron oxide and aluminium is called thermite reaction.
$\ce{Fe2O3 + 2Al -> Al2O3 + 2Fe + Heat}$
This reaction is used in welding railway tracks.
Important Exam Questions
One Mark Questions
- What is ductility?
- What is an alloy?
- What is galvanization?
- Name a non-metal that conducts electricity.
Two Mark Questions
- Write properties of ionic compounds.
- Explain rusting of iron.
- Differentiate metals and non-metals.
Three and Four Mark Questions
- Explain thermite reaction.
- Explain metallurgy.
- Explain extraction of zinc.
- Draw electrolysis of copper diagram.
These questions are repeatedly asked in examinations.
Preparation Tips for Students
- Learn reactivity series thoroughly
- Practice all chemical equations
- Study properties of metals and non-metals carefully
- Learn definitions like ductility, malleability and galvanization
- Revise ionic compounds and alloys regularly
