Metals and Non-metals | Class 10 Science Notes

3.1.2 Non-metals

Non-metals are elements that generally lack the physical properties of metals. They are usually dull in appearance, brittle, and poor conductors of heat and electricity, with the notable exception of graphite, an allotrope of carbon that conducts electricity. Non-metals exist in all three physical states: solids (carbon, sulphur, iodine), liquids (bromine), and gases (oxygen, hydrogen). The section includes activities where students observe the physical properties of non-metals and compare them with metals. For example, non-metals cannot be beaten into sheets or drawn into wires, and they do not produce sound when struck. Some exceptions to general trends are noted, such as iodine which is lustrous, and carbon which exists in allotropes with very different properties: diamond is the hardest natural substance and an electrical insulator, while graphite is a good conductor. Alkali metals like sodium and potassium are soft enough to be cut with a knife, showing that physical properties alone are insufficient for classification. The section concludes that chemical properties are more reliable for distinguishing metals and non-metals.

📊 Diagram: Table on page 3 (2×8)

🧪 Activity: Activity 3.7 involves testing physical properties of non-metals such as carbon, sulphur, and iodine and comparing them with metals.

🔗 Connection: Leads to chemical properties of metals and non-metals, which provide clearer classification.

Table on page 3 (2×8)

Table on page 10 (5×5)

Table on page 13 (2×1)

| 1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.

Table on page 19 (4×4)