f-block elements exhibit different oxidation states, color, complex formation like properties. The size of lanthanoids decrease due to poor screening effect of 4f electrons. It is called lanthanoid contraction. Lanthanoid hydroxides are basic in nature. choose the correct order of ionic radius from the given options( where atomic numbers of Ce, Pr, Eu and Dy are 58 59 63 and 66 respectively)

In the modern periodic table, elements are arranged in order of increasing atomic numbers, which is related to the electornic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, s, p,d and f. The modern periodic table consists of 7 periods and 18 groups. Each period begins with the filling of a new energy shell. in accordance with the Aufbau principal, the seven periods (1 to 7) have 2,8,8,18,18,32 and 32 elements respectively. The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthanoids and actinoids, are placed at the bottom of the main body of the periodic table Which of the element whose atomic numbers are given below, cannot be accommodated in the present set up of the long form of the periodic table ?

Both alkali metals and alkaline earth metals are s- block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. Be^(2+) ion is very small and exerts a high polarising effect on any anion associated with it. Which of the bicarbonate does not exist in solid state?

Both alkali metals and alkaline earth metals are s- block elements. They resemble each other in many respects but still there are certain dissimilarities in their properties due to different number of electrons in the valence shell, different atomic radii, ionisation enthalpy, electronegativity, etc. Like lithium, Be also differs from rest of the alkaline earth metals on account of its small atomic size and high electronetativity. Be^(2+) ion is very small and exerts a high polarising effect on any anion associated with it. The correct sequence of increasing covalent character is

Comprehension given below is followed by some multiple choice questions. Each question has one correct option. Choose the correct option. In the modern periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, viz s, p, d and f. The modern periodic table consists of 7 periods and 18 groups. Each, period begins with the filling of a new energy shell. In accordance with the Aufbau principle, the seven periods (1 to 7) have 2, 8, 8, 18, 18, 32 and 32 elements respectively. The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthonoids and actinoids are placed at the bottom of the main body of the periodic table (iv) The electronic configuration of the element which is just above the element with atomic number 43 in th same group is ...........

Comprehension given below is followed by some multiple choice questions. Each question has one correct option. Choose the correct option. In the modern periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, viz s, p, d and f. The modern periodic table consists of 7 periods and 18 groups. Each, period begins with the filling of a new energy shell. In accordance with the Aufbau principle, the seven periods (1 to 7) have 2, 8, 8, 18, 18, 32 and 32 elements respectively. The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthonoids and actinoids are placed at the bottom of the main body of the periodic table (ii) The last element of the p-block in 6th period is represented by the outermost electronic configuration.

When an atom or an ion is missing from its normal lattice site, a lattice vacancy (Schottky defect) is created. In stoichimetric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charged ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This is the Frenkel defect commonly found along with the Schottky defects and interstitials. In pure alkali halides, Frenkel defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unlike Schottky defects, Frenkel defects do not change the denstiy of the solids. In certain ionic solids (e.q. AgBr) both Schottky and Frenkel defects occur. The defects discussed above do not disturb the stoichiometry of the crystalline material. There is large variety of non-stoichiomertic inorganic solids which contain an excess or deficiency of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an inmportant group of solids. For example in the vanadium oxide, VO_(x) , x can be anywhere between 0.6 and 1.3. There are solids which are difficult to prepare in the stoichiometric composition. Thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a composition of Fe_(0.95)O but it may range from Fe_(0.93)O " to " Fe_(0.96)O ). Non-stoichiometric behaviour is most commonly found for transition metal compounds though is also known for some lanthanoids and actinoids. Zinc oxide loses oxygen reversibly at high temperature and turns yellow in colour. The excess metal is accommodated interstitially, giving rise to electrons trapped in the neighbourhood. The enhanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons.ltrbgt Anion vacancies in alkali halides are produced by heating the alkali halide crystals in an atmosphere of the alkali metal vapur. When the metal atoms deposit on the surface they diffuse into the crystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped in anion vacancies are referred to as F-centers (from Farbe the German word for colour) that given rise to interesting colour in alkali halides. Thus, the excess of potassium in KCl makes the crytal appear violet and the excess of lithium in LiCl makes it pink. Stongly heated ZnO crystal can conduct electricity. This is due to

When an atom or an ion is missing from its normal lattice site, a lattice vacancy (Schottky defect) is created. In stoichimetric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charged ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This is the Frenkel defect commonly found along with the Schottky defects and interstitials. In pure alkali halides, Frenkel defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unlike Schottky defects, Frenkel defects do not change the denstiy of the solids. In certain ionic solids (e.q. AgBr) both Schottky and Frenkel defects occur. The defects discussed above do not disturb the stoichiometry of the crystalline material. There is large variety of non-stoichiomertic inorganic solids which contain an excess or deficiency of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an inmportant group of solids. For example in the vanadium oxide, VO_(x) , x can be anywhere between 0.6 and 1.3. There are solids which are difficult to prepare in the stoichiometric composition. Thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a composition of Fe_(0.95)O but it may range from Fe_(0.93)O " to " Fe_(0.96)O ). Non-stoichiometric behaviour is most commonly found for transition metal compounds though is also known for some lanthanoids and actinoids. Zinc oxide loses oxygen reversibly at high temperature and turns yellow in colour. The excess metal is accommodated interstitially, giving rise to electrons trapped in the neighbourhood. The enhanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons.ltrbgt Anion vacancies in alkali halides are produced by heating the alkali halide crystals in an atmosphere of the alkali metal vapur. When the metal atoms deposit on the surface they diffuse into the crystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped in anion vacancies are referred to as F-centers (from Farbe the German word for colour) that given rise to interesting colour in alkali halides. Thus, the excess of potassium in KCl makes the crytal appear violet and the excess of lithium in LiCl makes it pink. When LiCl is heated into the vapour of lithium, the crystal acquires pink colour. This is due to