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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
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How would you explain the lower atomic radius of Ga as compared to Al?
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Ionisation enthalpy (∆iH1kJ mol–1) for the elements of Group 13 follows the order.
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Which of the following statements are correct. Answer on the basis of Figure.
(i) The two birdged hydrogen atoms and the two boron atoms lie in one plane;
(ii) Out of six B – H bonds two bonds can be described in terms of 3 centre 2-electron bonds.
(iii) Out of six B – H bonds four B – H bonds can be described in terms of 3 centre 2 electron bonds;
(iv) The four-terminal B – H bonds are two centre-two electron regular bonds.
Explain why the following compounds behave as Lewis acids?
BCl3
Explain why the following compounds behave as Lewis acids?
AlCl3
Complete the following chemical equations:
\[\ce{Z + 3 LiAlH4 -> X + 3LiF + 3AlF_3}\]
\[\ce{X + 6H2 -> Y + 6H2}\]
\[\ce{3X + 3O2 ->[Δ] B2O3 + 3H2O}\]
Match the species given in Column I with the properties mentioned in Column II.
| Column I | Column II |
| (i) \[\ce{BF^{-}4}\] | (a) Oxidation state of central atom is +4 |
| (ii) AICI3 | (b) Strong oxidising agent |
| (iii) SnO | (c) Lewis acid |
| (iv) PbO2 | (d) Can be further oxidised |
| (e) Tetrahedral shape |
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 |
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Atomic size
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TlCl3, TlCl
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Boron compounds behave as Lewis acids because of their ______.
