Groups with `-M` effect decrease the electron density of the rest of the molecule
eg- `-COOH, -COOR, -CHO, -COR, -CO-, -CN, -NO_(2), -SO_(3)H` etc

Groups with +M effect increase the electron density of the rest of the molecule eg Cl, -Br, -I, -NH_(2), NHR, NR_(2), -OH,-OR, -OCOR, -NHCOR etc

Find the number of electron - donating groups in resonance among the following : {:("a) "-CONH_(2), "b) "-NO_(2), "c) "-OCOCH_(3), "d) "-COOCH_(3)), ("e) "-CHO, "f) "-NHCOCH_(3),"",""):}

PASSAGE - 3 : In modern periodic table there is gradation in the properties of elements. In a period the Ionisation energy, Electron affinity, Electro negativity, Non-Metallic nature increases. In a group the atomic size, metallic nature, reducing properties and densities of elements increases. In the compunds KO_2,Cr_2,O_3,SO_2 and Cl_2O_3 Which element shows more valency with respect to oxygen

When an electron withdrawing or electron releasing group is attached to carbon chain, polarity is induced on the carbon atom and on the substituent attach to it. This permanent polarity is due electron displacement due to difference in electronegativities this is called inductive effect or I effect. The inducitve effect depends in the electronegativity of the substituent. The inductive effect is broadly classified as (i) negative inductive effect or -I effect. (ii) positive inductive effect or +I effect. Stability of given anions in the decreasing order is (i) bar(C)H_(3) " (ii) "bar(C)H_(2)-NO_(2)" (iii) "bar(C)H_(2)Cl" (iv) "CH_(3)-bar(C)H_(2)

The number of electrophiles and nucleophiles present in the species given below are respectively. BF_(3), CO_(2), Me_(3)N, SO_(3), CH_(3)overset(+)(CO), HS^(-), NO_(2)^(+), FeCl_(3), H_(2)O

The equivalent weights of oxidising and reducing agents can be calculated by the number of electrons gained or lost. The equivalent weight of an oxidising agent is the number of parts by weight of the substance which gains one electron. Thus, it is equal to the molecular weight of the substance divided by the number of electrons gained in the balanced chemical equation. Similarly, equivalent weight of a reducing agent is equal to the molecular weight divided by the number of electrons lost as represented in the balanced chemical equation The equivalent weght of As_(2),S_3 in the following reaction As_(2)S_(3) + H^(+) + NO_(3)^(-) rarr NO + H_(2)O + AsO_(4)^(3-) + SO_(4)^(2-) is related to its molecular weight as

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. The size of iso electronic species -F^(-) , Na^(+) and Mg^(2+) is effected by

In octahedral complexes having co-ordination number 6, the degeneracy of the d-orbitals of central atom is removed due to ligand electron metal electron repulsions. In the octahedral complex three orbitals have lower energy, t_(2g) set and two orbitals have higher energy, eg set. This phenomenon is formed as crystal field splitting and the energy seperation is denoted by Delta_(0) . Thus the energy of the two eg orbitals will increase by (3//5)Delta_(0) and that of the three t_(2g) will decrease by (2//5)Delta_(0) . The erystal field splitling, Delta_(0) depends upon the field produced by the ligand and charge on the metal ion. Some ligands are able to produce strong field and in these cases, the splitting will be large whereas other produce weak fields and consequently result in small splitting of d-orbitals. Predict the order of Delta_(0) for the following compound i) [Fe(H_(2)O)_(6)]^(+2) ii) [Fe(CN)2(H_(2)O)_(4) iii) [Fe(CN)_(4)(H_(2)O)_(2)]^(2-)