Short Answer TypePredict the formulae of the stable binary compounds that would be formed by the following pairs of elements:
calcium and iodine
Predict the formula of the stable binary compounds which would be formed by the following pairs of elements:
(i) element 114 and fluorine
(ii) element 120 and oxygen.
Long Answer TypeDiscuss briefly the anomalous behviour of elements of second period.
Or
The first element of each group differs significantly from rest of the elements of the same group. Give reasons.
Short Answer TypeShow by a chemical reaction with water that Na2O is a basic oxide and Cl2O7 is an acidic oxide.
What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?
Long Answer TypeOn the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.
Short Answer TypeExplain why cation are smaller and anions larger in radii than their parent atoms?
The ionic radius of a cation is always smaller than the parent atom because a cation is formed by loss of one or more electrons by the neutral atom. The loss of one or more electrons increases the effective nuclear charge. As a result, the force of attraction of nucleus for the electrons increases and hence their ionic radii decrease. In contrast, the ionic radius of anion is formed by the addition of one or more electrons to the anion is formed by the addition of one or more electrons to the neutral atom. The addition of one or more electrons decreases the effective nuclear charge. As a result, the force of attraction of the nucleus for the electrons decreases and hence the ionic radii increases.
Long Answer TypeAmong the second period elements the actual ionisation enthalpies are in the order
Li<B<Be<C<O<N<F<Ne.
Explain why
(i) Be has higher 
than B
(ii) O has lower 
than N and F?
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