KEY NOTES 2-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals

Key Notes 2-Class 10 – Science -Chemistry -Chapter 3 – Metals and Non-metals  

Non- Metals:

Non metals are elements which form negative ions by gaining electrons. They are know as electronegative elements because they can form negative ions by gaining electrons.

 Physical Properties of Non-Metals:

Luster: Typically lack a shiny or metallic luster; often appear dull.

Malleability: Generally brittle and can easily break or crumble.

Ductility: Cannot be drawn into thin wires.

Conductivity: Poor conductors of heat and electricity.

Melting and Boiling Points: Generally have lower melting and boiling points compared to metals.

State at Room Temperature: Can exist in various states at room temperature, including solids, liquids, and gases.

Density: Lower density compared to metals.

Brittleness: Generally brittle and can break easily.

Insolubility in Water: Often insoluble or only slightly soluble in water.

Dull or Non-Metallic Luster: Lack the characteristic metallic shine.

Varied Colors: Can exhibit a variety of colors. For example, sulfur can be yellow or red.

 Chemical Reaction :

1. Reaction with Water: Generally do not react with water, except for some metalloids like phosphorus.

Example P₄ +6HCl à 2H₂ S + 3Cl₂

2. Reaction with Acids: Often do not react with acids, but some non-metals like sulphur can react.

Eg : S + 6HCl à 2H₂ S +3Cl₂

3. Reaction with Salt Solution: Generally do not displace metals from their salt solutions.

Example: No typical displacement reaction observed.

4. Reaction with Chlorine: Can react with chlorine to form chlorides which are non- electrolyts.

Example: S + Cl₂ à SCl₂

5. Reaction with Hydrogen:

Non-Metals: Can react with hydrogen to form hydrides.

Example: N₂ +3H₂ à 2NH₃

Uses of non metals:

Oxygen is vital for respiration.

Nitrogen is used in fertilizers.

Chlorine is used in disinfectants.

Metalloids:

A subset of elements known as metalloids shares properties of both metals and non-metals. They exhibit an intermediate range of characteristics and include elements like silicon, germanium, and boron.