(i) Give the formula which expresses the general electronic configuration of actinoids.
(ii) Which complexes are formed when actinoid halides react with alkali metal halides?
(iii) Why do actinoids get tarnished in air.

Give the general electronic configuration of actinoids

General electronic configuration of actinoids is (n-2)f^(1-14)(n-1)d^(0-2)ns^(2) . Which of the following actinoids have one electron in 6d orbital?

Name the alkali metals which form superoxides when heated in excess of air.

Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element.

(a) How is the valency of an element determined if its electronic configuration is known? Determine the valency of an element of atomic no. 9 (b) Given below are some elements of the Modern Periodic Table. Atomic numbers of the elements are given in the parentheses: A(4), B(9), C(14), D(19), E(20) (i) With the help of the electronic configuration, find out which one of the above elements will have one electron in its outermost shell? (ii) Which rwo elements belong to the same group? Give reasons for your answer. (iii) Which one of the above elements belonging to the fourth period has bigger atomic radius and why?.

(a) When a chromite ore (A) is fused with an aqueous solution of sodium carbonate in free excess of air, a yellow solution of compound (B) is obtained. This solution is filtered and acidified with sulphuric acid to form compound (C). Compound (C) on treatment with solution of KCl gives orange crystals of compound (D). Write the chemical formulae of compounds A to D. (b) Describe the cause of the following variations with respect to lanthanoids and actinoids: (i) Greater range of oxidation states of actinoids as compared to lanthanoids. (ii) Greater actinoid contraction as compared to lanthanoid contraction. (iii) Lower ionisation enthalpy of early actinoids as compared to the early lanthanoids.

Write the chemical formula and name of the compound which is the active ingredient of all alcoholic drinks. List its two uses. Write chemical equation and name of the product formed when this compound reacts with- (i) sodium metal (ii) hot concentrated sulfuric acid

The elements of group II are known as alkaline earth metals. The electronic configuration of these elements is ns^(2) and oxidation state is +2 . They have higher ionization energy than alkali metals in their respective period due to their small size and completely filled s-orbital. These elements give characteristic colour to bunsen flame. magnesium is used in the preparation of Grignard agent (RMgX) which is used in organic chemistry for preparation of sevaral organic compounds like alcohols. acids, hydrocarbons. Q. The reaction of RMgX with water will produces

The elements of group II are known as alkaline earth metals. The electronic configuration of these elements is ns^(2) and oxidation state is +2 . They have higher ionization energy than alkali metals in their respective period due to their small size and completely filled s-orbital. These elements give characteristic colour to bunsen flame. magnesium is used in the preparation of Grignard agent (RMgX) which is used in organic chemistry for preparation of sevaral organic compounds like alcohols. acids, hydrocarbons. Q. The correct order of 1st ionization energy is

When an atom or an ion is missing from its nomal lattice site a lattice vacanecy (Schottky defect) is created. In stoichmeteric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charge 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 id the Frenkel defect commonly found along with the Schottky defects and interstitial. In pure alkali halides. Frenked 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. Unike Schottky defects, Frenkel defect do not change the density of the solids. in certain ionic solids (e.g., AgBr) both schottky and Frenkel defect occur. The Defects idiscussed above do not disturb the stoichiometery of the crystalline material. there is large variety of non-stoichiometric inorganic solids which contains an excess or deficienty of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an important group of solids. For example in the vanadium oxide, VO_(x),x can be anywehere between 0.6 and 1.3 there are solids such as difficult to prepare in the soichiometric omposition thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a compositiion of Fe(0.95) O but it may range from Fe_(0.93) O to Fe_(0.96)O ). Non-stoichiometric behavious is most commonly found for transition metal compounds through is also known for some lathanoids and actinoids. Zinc oxide loses oxygen reversible at high temperature and turns yellow in colour. the excess metal is accomodated interstitial, giving rise to electrons trapped in the neighbourhood, the enchanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons. Anion vacancies in alkali halides are produced by heating the alkali halid crystals in an atmosphere of the alkali metal vapour. when the metal atoms deposit on the surface they diffuse into the cystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped i anion vacancies are referred to as F-centers (From Farbe the German word for colouf) that gives rise to interesting colour in alkali halides. Thus, the excess of potassium i KCl makes the crystal appear violet and the excess of lithium in LiCl makes it pink. Which of the following is most appropritate crystal to show Fremkel defect ?