CBSE Notes Class 10  Chapter 3 - Metals and Non Metals

Understanding the properties and applications of metals and non-metals is a fundamental part of the CBSE Class 10 Science curriculum, as outlined in the NCERT textbook. This comprehensive guide offers detailed CBSE notes on Chapter named Metals and Non-Metals, designed to help students grasp key concepts and prepare effectively for their exams.

1.0What are Metals and Non-Metals

The periodic table broadly categorizes elements into metals and non-metals, each possessing distinct properties. Metals like aluminum and copper are known for their high thermal and electrical conductivity and are widely used in construction, electronics, and transportation. On the other hand, non-metals such as sulfur and phosphorus are insulators and play essential roles in various biological and chemical processes. Understanding whether an element is a metal or non-metal helps in determining its applications and behavior in different environments.

2.0Physical Properties of Metals and Non-Metals

3.0Chemical Properties of Metals and Non-Metals

Here are some examples of Chemical Reactions:

Reaction with Oxygen

• Metals: 2Mg(s) + O₂(g) → 2MgO(s) 
• Non-Metals: C(s) + O₂(g) → CO₂(g)

Reaction with Water

• Metals: 2Na(s) + 2H₂O(l) → 2NaOH (aq) + H₂(g)
• Non-Metals: CO₂(g) + H₂O(l) → H₂CO₃ (aq)

Reaction with Acids

• Metals: Zn(s) + 2HCl (aq) →ZnCl₂(aq) +H₂ (g)
• Non-Metals: Non-metals generally do not react with acids to produce hydrogen gas.

Reaction with Bases (mostly applicable to non-metals)

• Non-Metals: Cl₂(g) + 2NaOH(aq) → NaCl(aq) + NaClO(aq) + H₂O(l)

4.0Reactivity Series and its Significance

The reactivity series is a list of metals arranged in order of their reactivity from highest to lowest. It is used to predict the products of displacement reactions and the method used for extracting metals.

Here is a simplified version of the reactivity series from the most reactive to the least:

• Potassium (K)
• Barium (Ba)
• Sodium (Na)
• Calcium (Ca)
• Magnesium (Mg)
• Aluminum (Al)
• Zinc (Zn)
• Iron (Fe)
• Nickel (Ni)
• Tin (Sn)
• Lead (Pb)
• Hydrogen (H)
• Copper (Cu)
• Mercury (Hg)
• Silver (Ag)
• Gold (Au)
• Platinum (Pt)

5.0Occurrence of Metals

Metals are found in the Earth’s crust either as native metals (pure form) or more commonly as minerals within ores. Ores require processing to extract the metal.

6.0Extraction of Metals

The extraction process involves several steps to convert raw ore into purified metal, considering the metal’s position in the reactivity series.

• Enrichment of Ores: This is the process of increasing the concentration of metals in ores by removing impurities and other non-metallic elements, often through physical or chemical means such as flotation and leaching.
• Extracting Metals Low in the Activity Series: Metals low in the activity series (like copper and silver) are often found in a free state and can be extracted simply by heating their oxides with carbon or carbon monoxide.
• Extracting Metals from the Middle of the Activity Series: Metals, which are present  in the middle of the activity series (like zinc and iron) are extracted by reducing their oxides with carbon or carbon monoxide at high temperatures.
• Refining of Metals: Refining is the final step in metal extraction, where impurities are removed from the crude metal to achieve high purity. Techniques include electrolytic refining, distillation, and chemical methods.

• Corrosion: Corrosion is the deterioration of metals caused by chemical reactions with their surrounding environment, typically involving oxygen (rusting of iron). Preventative measures include galvanization, painting, and using anti-corrosive alloys.

7.0Uses of Metals and Non-Metals

Metals:

• Iron: Used in construction and manufacturing machinery.
• Copper: Used in electrical wiring due to its excellent electrical conductivity.
• Aluminum: Used in packaging, transport, and construction because of its low density.

Non-Metals:

• Oxygen: Essential for respiration and used in medical treatments.
• Carbon: Used in filters, pencils, and as a fuel in its various forms.
• Sulfur: Used in the manufacture of fertilizers and gunpowder.

8.0Solved Examples

Example 1.What happens when zinc granules are treated with dilute hydrochloric acid? Write the chemical equation for the reaction and describe the test for the gas evolved.

Solution: When zinc granules react with dilute hydrochloric acid, hydrogen gas is evolved, and zinc chloride is formed.

Reaction: Zn + 2HCl → ZnCl₂ + H₂​

The gas that evolved is hydrogen. To test for hydrogen gas, bring a burning splinter near the mouth of the test tube. If hydrogen gas is present, it will burn with a pop sound.

Example 2.Why do non-metals not conduct electricity? Name one non-metal that conducts electricity and explain why it is an exception.

Solution: Non-metals do not conduct electricity because they lack free electrons or ions that can move to carry an electric charge. However, graphite is an exception. It is a form of carbon (a non-metal) that conducts electricity because it has delocalized electrons within its structure that are free to move, allowing it to conduct electricity.

Example 3.What happens when sodium reacts with water? Write the balanced chemical equation and mention the type of reaction.

Solution: Sodium reacts vigorously with water, producing sodium hydroxide (a strong base) and hydrogen gas. The reaction is highly exothermic, and the hydrogen gas evolved may catch fire.

Reaction: 2Na + 2H₂O → 2NaOH + H₂

This is a displacement reaction because sodium displaces hydrogen from water.