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Classification of Elements and Periodicity in Properties

Short Answer Type

171.

Predict the formulae of the stable binary compounds that would be formed by the following pairs of elements:
calcium and iodine

113 Views

172.

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.

226 Views

Long Answer Type

173.

Discuss 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.

248 Views

174.
What do you understand by diagonal relationship?

Certain elements resemble closely one-step down in the next higher group in the periodic table. The resemblance in properties of a member of the group and a diagonally situated element of the adjacent group is called diagonal relationship. For example, the first three elements of the second period (Li. Be. B) show diagonal similarity with elements (Mg, AI, Si) of the third period placed on the right-hand side.

Cause of diagonal relationship. The cause of the diagonal relationship is due to opposing trends in periodic properties along a period and down the group. For example,
(i) The electropositive character increases down a group and it decreases from left to right in a period. Consequently, diagonally opposite elements in the periodic table have more or less similar electropositive character and hence, in turn, have many similar properties also.
(ii) In case of metallic elements, the diagonally opposite metals possess nearly similar polarizing power [i.e. ionic charge/(ionic radius)²] because:
(a) ionic charge increases from left to right in a period and
(b) ionic radius decreases from left to right in a period but increases down a group.

1285 Views

Short Answer Type

175.

Show by a chemical reaction with water that Na₂O is a basic oxide and Cl₂O₇ is an acidic oxide.

374 Views

176.

What is the basic theme of organisation in the periodic table?

273 Views

177.

What is the basic difference in approach between the Mendeleev’s Periodic Law and the Modern Periodic Law?

221 Views

Long Answer Type

178.

On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

419 Views

Short Answer Type

179.

Explain why cation are smaller and anions larger in radii than their parent atoms?

136 Views

Long Answer Type

180.

Among 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 $increment subscript straight i straight H$ than B
(ii) O has lower $increment subscript straight i straight H$ than N and F?