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प्रश्न
Explain the basis of differences between metallic and ionic crystals.
फरक स्पष्ट करा
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उत्तर १
- The primary differences between ionic and metallic crystals are brittleness, hardness, and electrical conductivity.
- The characteristics of electrostatic attraction and electron mobility in the metals serve as the foundation for these variations.
- Electrostatic forces between oppositely charged ions that are fixed at the lattice sites are present in ionic solids.
- They can’t conduct currents because of this. Kernels and mobile valence electrons in metallic materials are electrically attracted to one another.
- Metals are excellent electrical conductors because of the mobility of their valence electrons.
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उत्तर २
| Property | Metallic Crystals | Ionic Crystals | |
| 1. | Constituents | These are composed of positive metal ions immersed in a sea of delocalised electrons. | These consist of both positive and negative ions held together by strong electrostatic forces. |
| 2. | Bonding | The atoms are bonded through metallic bonding, which involves a lattice of positive ions surrounded by free-moving electrons. | The ions are held together by strong ionic (Coulombic) attraction between oppositely charged ions. |
| 3. | Electrical Conductivity | They are good conductors of electricity due to the presence of free-moving electrons. | They conduct electricity only in the molten state or when dissolved in water, as the ions are free to move. |
| 4. | Malleability & Ductility | They are highly malleable and ductile and can be hammered or drawn into wires without breaking. | They are brittle and tend to shatter when subjected to stress due to repulsion between like-charged ions on displacement. |
| 5. | Melting & Boiling Points | These generally have high melting and boiling points, although the values may vary depending on the metal. | They usually have high melting and boiling points due to strong ionic bonds, not conductivity (the original line had an error). |
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पाठ 1: Solid State - 'NCERT TEXT-BOOK' Exercises [पृष्ठ ५३]
