Explain the basis of similarities and differences between metallic and ionic crystals.
|
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. |
How will you distinguish between the following pairs of terms:
Crystal lattice and unit cell?
'Stability of a crystal is reflected in the magnitude of its melting points. Comment. Collect melting points of solid water, ethyl alcohol, diethyl ether and methane from a data book. What can you say about the inter molecular forces between these molecules?
How will you distinguish between the following pairs of terms:
Hexagonal close-packing and cubic close-packing?
How will you distinguish between the following pairs of terms:
Tetrahedral void and octahedral void?
