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प्रश्न
Answer the following in brief.
Distinguish between ionic solids and molecular solids
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उत्तर
| Ionic solids | Molecular solids |
| 1. The constituent particles are charged ions (cations and anions). | 1. The constituent particles are monoatomic or polyatomic molecules |
| 2. The constituent particles are held by the electrostatic force of attraction between oppositely charged ions. | 2. The constituent particles are held by intermolecular forces of attractions such as London forces, dipole-dipole forces and/or hydrogen bonds. |
| 3. They are hard and brittle. | 3. They are soft. |
| 4. They have high melting points. | 4. They have low melting points. |
| 5. They are nonconductors of electricity in solid-state. However, they are good conductors when melted or dissolved in water. | 5. They are poor conductors of electricity. |
| 6. e.g. NaCl, CaF2, etc. | 6. Ice, benzoic acid, etc. |
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संबंधित प्रश्न
Explain the basis of similarities between metallic and ionic crystals.
Explain ionic solids are hard and brittle.
An ionic compound crystallises in FCC type structure with ‘A’ ions at the centre of each face and ‘B’ ions occupying corners of the cube. The formula of compound is _______.
Define Anisotropy.
A compound is made up of two elements X and Y and crystallizes in bcc structure. Atoms of X are present at the corners of the cube. Atoms of Y are present at the centre of the cube. The formula of the compound is ______.
Classify the following solid:
Pb
An ionic compound AxBy crystallizes in fcc type crystal structure with B ions at the centre of each face and A ion occupying corners of the cube. the correct formula of AxBy is
Assertion: monoclinic sulphur is an example of a monoclinic crystal system
Reason: for a monoclinic system, a ≠ b ≠ c and α = γ = 90°, β ≠ 90°
The ionic radii of A+ and B− are 0.98 × 10−10 m and 1.81 × 10−10 m. The coordination number of each ion in AB is ______.
Give any three characteristics of ionic crystals.
Classify the following solid.
P4
Solid X is a very hard electrical insulator in solid as well as in molten state. It melts at extremely high temperature. Solid X is a ____________.
Silicon carbide is an example of ____________.
London forces are present in ____________.
The hardest substance among the following is:
Solid CH4 is ____________.
An example of a covalent crystalline solid is ____________.
Among solids, the highest melting point is exhibited by ____________.
Which one of the following forms a molecular solid when solidified?
Which of the following cannot be regarded as molecular solid?
(i) SiC (Silicon carbide)
(ii) AlN
(iii) Diamond
(iv) I2
How many chloride ions are surrounding sodium ions in sodium chloride crystal?
Which of the following is not true about the ionic solids?
An excess of potassium ions makes KCl crystals appear violet or lilac in colour since:
(i) some of the anionic sites are occupied by an unpaired electron.
(ii) some of the anionic sites are occupied by a pair of electrons.
(iii) there are vacancies at some anionic sites.
(iv) F-centres are created which impart colour to the crystals.
Inspite of long range order in the arrangement of particles why are the crystals usually not perfect?
Calculate the angle at which first order reflection will occurs in an X-ray spectrometer when x ~ rays of wavelength \[\ce{1.54 \overset{\circ}{A}}\] are diffracted by the atoms of a crystal given that inter planer distance is \[\ce{0.04 \overset{\circ}{A}}\]
The major binding force in diamond, silicon and quartz is ______.
A reddish-pink substance on heating gives off a vapour which condenses on the sides of the test tube and the substance turns blue. If on cooling water is added to the residue it turns to original colour. The substance is ______.
Among the following which is the best description of water in the solid phase?
