Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

2

(a)

All transition elements are d-block elements, but all d-block elements are not transition elements. Explain.

2

(a)

List the factors that can influence the ionic radius of an element.

2

(a)

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

2

(a)

The first ionization enthalpy values (in kJ mol^–1) of group 13 elements are :

B	Al	Ga	In	Tl
801	577	579	558	58

How would you explain this deviation from the general trend ?

2

(a)

The increasing order of reactivity among group 1 elements is Li < Na < K < Rb whereas that among group 17 elements is F > CI > Br > I. Explain.

2

(a)

Write the general outer electronic configuration of s-, p-, d- and f- block elements.

2

(a)

State the Modern Periodic Law.

2

(a)

Give four examples of species which are isoelectronic with ca²⁺

2

(a)

Which two elements of the following belong to the same period? AI, s; Ba and O

2

(a)

What are representative elements?

2

(a)

Give general electronic configuration off-block elements?

2

(a)

The electronic configuration of an element is 1s² 2S² 2p⁶ 3s² 3p⁶ 4s¹. Locate the element in the periodic table.

2

(a)