Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Physical properties of metals include being malleable (can be beaten into thin sheets), ductile (can be drawn into wires), sonorous (produce a ringing sound), and having a metallic lustre (shiny surface).
Metals are generally good conductors of heat and electricity, while non-metals are poor conductors, with the exception of graphite which conducts electricity.
Metals react with oxygen to form metal oxides, which are basic in nature. For example, . Basic oxides turn red litmus paper blue.
Non-metals react with oxygen to form non-metallic oxides, which are generally acidic. For example, . These oxides turn blue litmus paper red when dissolved in water to form acids like .
Reactivity series: Some metals are highly reactive (like Sodium and Potassium) and react vigorously with water and air, while others (like Gold and Silver) are very stable.
Displacement Reaction: A more reactive metal displaces a less reactive metal from its salt solution. For example, iron displaces copper from copper sulphate solution: .
Corrosion: The process where metals are eaten away gradually by the action of air, moisture, or chemicals. Rusting of iron is a common example represented by .
📐Formulae
💡Examples
Problem 1:
A piece of magnesium ribbon is burnt in the air and the resulting ash is dissolved in water. What is the nature of the solution formed?
Solution:
The solution is basic in nature.
Explanation:
When magnesium burns, it forms Magnesium Oxide (). When is dissolved in water, it forms Magnesium Hydroxide (), which is a base. This solution will turn red litmus paper blue.
Problem 2:
Explain the reaction when an iron nail is placed in a beaker containing blue-colored copper sulphate () solution.
Solution:
Explanation:
Iron is more reactive than copper. It displaces copper from the copper sulphate solution, forming green-colored iron sulphate () and a reddish-brown deposit of copper on the iron nail.
Problem 3:
Why is Sodium metal stored in kerosene?
Solution:
To prevent it from reacting with moisture and oxygen in the air.
Explanation:
Sodium is a highly reactive metal. It reacts vigorously with the oxygen and moisture () present in the air, catching fire. Storing it in kerosene cuts off the contact with air and water.