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प्रश्न
Describe the general trends in the following properties of the elements in Groups 13 and 14.
Ionisation enthalpy
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उत्तर
In group 13, the standardised trend of decrease of Ionisation enthalpy is not monitored.
As we move from Boron to Aluminium the atomic size increases and ionisation enthalpy decreases but when we move ahead from Aluminium to Gallium, the screening effect of 3d electrons comes into play. The poor shielding effect of the electrons lead to the increase in nuclear charge on the valence electrons and results in increase of ionisation enthalpy.
Moving from gallium to Indium, due to The shielding effect of 4d electrons the ionisation enthalpy decreases.
From Indium to thallium, 4f electrons come into action their poor shielding effect increases the effective nuclear charge on valence electrons hence the ionisation of Thallium energy further increases.
The decreasing order of ionization enthalpy for group-13 elements will be: B > Ti > Ga > Al > In
As we move down in group 14 the ionisation enthalpy decreases in the order: C > Si > Ge > Pb > Sn
On moving down the group the size of the atom increases which results in the large decrease in ionisation energy from carbon to silicon but as we move from silicon to heavier metals small decrease in the ionisation energy is observed. This is mainly due to the less screening effect of d-electrons in germanium and tin, and due to fully filled d and f electrons in lead.
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संबंधित प्रश्न
Aluminium trifluoride is insoluble in anhydrous HF but dissolves on the addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous BF3 is bubbled through. Give reasons.
What happens when BF3 is reacted with ammonia?
What do you understand by inert pair effect?
The exhibition of highest co-ordination number depends on the availability of vacant orbitals in the central atom. Which of the following elements is not likely to act as central atom in \[\ce{MF^{3-}6}\]?
In the structure of diborane ______.
Explain the following:
Boron does not exist as B3+ ion.
Explain the following:
Electron gain enthalpy of chlorine is more negative as compared to fluorine.
Explain the following:
Tl (NO3)3 acts as an oxidising agent.
Identify the compounds A, X and Z in the following reactions:
\[\ce{A + 2HCl + 5H2O -> 2NaCl + X}\]
Match the species given in Column I with properties given in Column II.
| Column I | Column II |
| (i) Diborane | (a) Used as a flux for soldering metals |
| (ii) Galluim | (b) Crystalline form of silica |
| (iii) Borax | (c) Banana bonds |
| (iv) Aluminosilicate | (d) Low melting, high boiling, useful for measuring high temperatures |
| (v) Quartz | (e) Used as catalyst in petrochemical industries |
Match the species given in Column I with the hybridisation given in Column II.
| Column I | Column II |
| (i) Boron in [B(OH)4]– | (a) sp2 |
| (ii) Aluminium in [Al(H2O)6]3+ | (b) sp3 |
| (iii) Boron in B2H6 | (c) sp3d2 |
| (iv) Carbon in Buckminsterfullerene | |
| (v) Silicon in \[\ce{SiO^{4-}4}\] | |
| (vi) Germanium in [GeCl6]2– |
Account for the following observations:
Though fluorine is more electronegative than chlorine yet BF3 is a weaker Lewis acid than BCl3
Account for the following observations:
PbO2 is a stronger oxidising agent than SnO2
Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.
AlCl3 , AlCl
Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.
InCl3, InCl
A nonmetallic element of group 13, used in making bullet proof vests is extremely hard solid of black colour. It can exist in many allotropic forms and has unusually high melting point. Its trifluoride acts as Lewis acid towards ammonia. The element exihibits maximum covalency of four. Identify the element and write the reaction of its trifluoride with ammonia. Explain why does the trifluoride act as a Lewis acid.
Taking stability as the factor, which one of the following represents the correct relationship?
