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Class 10 Class 12

Explain the basis of similarities and differences between metallic and ionic crystals.

The similarities and differences between metallic and ionic crystals are described as below:
 Characteristics Ionic crystals Metallic crystals 1. Constituent particles cations (positive ions) and anions (negative ions) Positive ions and mobile electrons. 2. Binding forces Strong electrostatic forces (electro valent bonding) Electrical attraction between positive ions and mobile electrons (metallic bonding) 3. Physical properties Hard and brittle; high m.p. and b.p. good conductors of heat and electricity in molten state and aqueous solution, high heat of fusion. Hard but malleable, high m.p., very good conductors of heat and electricity in solid and molten state, moderate heats of fusion.
204 Views

Classify the following as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Amorphous solids: Polyurethane, teflon, cellophane, polyvinyal chloride, fibre glass.
Crystalline solids: naphthlene, benzoic acid, potassium nitrate, copper.
1237 Views

Why are solids rigid?

Solids are rigid because the internuclear distance between the  molecules of a solid are very less and closely packed and their positions are fixed due to the strong forces of attraction between them.
2488 Views

Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show clevage property?

Refractive index of a solid which have the same value along all directions are isotropic in nature. It would not show cleavage property.
1055 Views

Why is glass considred a super-cooled liquid?

Glass is amorphous solids and  have a tendency to flow, though very slowly. Therefore, these are called pseudo solids or super cooled liquids .
1368 Views

Why do solids have a definite volume?

A solid have a definite volume because the inter molecular distance  between its molecules are fixed.
1439 Views