P BLOCK

B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Chapter 7: The p-Block Elements Top Concepts 1. p-Block elements: Elements belonging to groups 13 to 18 of the periodic table are called p-block elements. 2 1-6 2. General electronic configuration of p-block elements: The p-block elements are characterized by the ns np shell electronic configuration. valence 3. Representative elements: Elements belonging to the s and p-blocks in the periodic table are called the representative elements or main group elements. 2 4. Inert pair effect: The tendency of ns electron pair to participate in bond formation decreases with the increase in atomic size. Within a group the higher oxidation state becomes less stable with respect to the lower oxidation state as the atomic number increases. This trend is called ‘inert pair effect’. In other words, the energy required to unpair the electrons is more than energy released in the formation of two additional bonds. 5. Nitrogen family: The elements of group 15 – nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb) and bismuth (Bi) 2 3 belong to configuration is ns np . 6. Oxygen family: Group 16 of periodic table consists of five elements – oxygen (O), sulphur (S), selenium (Se), tellurium 2 4 (Te) and polonium (Po). Their general electronic configuration is ns np . 7. The halogen family: Group 17 elements, fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At), belong to 2 5 halogen family. Their general electronic configuration is ns np . 8. Group 18 elements: Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are Group 18 2 6 elements. They are also called noble gases. Their general electronic configuration is ns np except helium which 2 has electronic configuration 1s . They are called noble gases because they show very low chemical reactivity. GROUP 15 ELEMENTS 9. Atomic and ionic radii: Covalent and ionic radii increase down the group. There is appreciable increase in covalent radii from N to P. There is small increase from As to Bi due to presence of completely filled d or f orbitals in heavy elements. 10. Ionisation energy: It goes on decreasing down the group due to increase in atomic size. Group 15 elements have higher ionisation energy than group 14 elements due to smaller size of group 15 elements. Group 15 elements have higher ionization energy than group 16 elements because they have stable electronic configuration i.e., half-filled porbitals. 11. Allotropy: All elements of Group 15 except nitrogen show allotropy. 12. Catenation: Nitrogen shows catenation to some extent due to triple bond but phosphorus shows catenation to maximum extent. The tendency to show catenation decreases down the group. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change   Chapter 7  The p-Block Elements Top Concepts 1. p-Block elem...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 13. Oxidation states: The common oxidation states are +3, +5, –3. The tendency to show –3 oxidation state decreases down the group due to decrease in electronegativity which is due to increase in atomic size. The stability of +5 oxidation state decreases whereas stability of +3 oxidation state increases due to inert pair effect. Nitrogen shows oxidation states from –3 to +5. Nitrogen and phosphorus with oxidation states from +1 to +4 undergo oxidation as well as reduction in acidic medium. This process is called disproportionation. 3 HNO2 → HNO3 + H2O + 2 NO 3 14. Reactivity towards hydrogen: All group 15 elements from trihydrides, MH3. Hybridization sp The stability of hydrides decrease down the group due to decrease in bond dissociation energy down the group. NH3 > PH3 > AsH3 > SbH3 > BiH3 Boiling point: PH3 < AsH3 < NH3 < SbH3 < BiH3 Boiling point increases with increase in size due to increase in van der Waals forces. Boiling point of NH3 is more because of hydrogen bonding. Bond angle: NH3 (107.8°) > PH3 (99.5°) > AsH3 (91.8°) ≈ SbH3 (91.3°) > BiH3 (90°) Electronegativity of N is highest. Therefore, the lone pairs will be towards nitrogen and hence more repulsion between bond pairs. Therefore bond angle is the highest. After nitrogen, the electronegativity decreases down the group. Basicity decreases as NH3 > PH3 > AsH3 > SbH3 < BiH3. This is because the lone pair of electrons are concentrated more on nitrogen and hence the basicity will be maximum in the case of NH3. It will decrease down the group as the electronegativity decreases down the group. The reducing power of hydrides increases down the group due to decrease in bond dissociation energy down the group. 15. Reactivity towards oxygen: All group 15 elements from trioxides (M2O3) and pentoxides (M2O5). Acidic character of oxides decreases and basicity increases down the group. This is because the size of nitrogen is very small. It has a strong + positive field in a very small area. Therefore, it attracts the electrons of water’s O-H bond to itself and release H ions easily. As we move down the group, the atomic size increases. Hence, the acidic character of oxides decreases and basicity increases as we move down the group. 16. Reactivity towards halogen: Group 15 elements form trihalides and pentahalides. Trihalides – covalent compounds and become ionic down the group. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  13. Oxidation states  The common oxidation states are  3,  5,...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 3 sp hybridization, pyramidal shape 3 Pentahalides - sp d hybridization, TBP shape They are Lewis acids because of the presence of vacant d – orbitals. - - PCl5 + Cl → [PCl6] + - PCl is ionic in solid state and exist as [PCl ] [PCl ] 5 4 6 In PCl5, there are three equatorial bonds and two axial bonds. The axial bonds are longer than equatorial bonds because of greater repulsion from equatorial bonds. Nitrogen does not form pentahalides due to absence of d- orbitals. 17. Reactivity towards metals: All elements react with metals to form binary compounds in –3 oxidation state. 18. Anomalous behavior of nitrogen: The behavior of nitrogen differs from rest of the elements. Reason: i. It has a small size. ii. It does not have d – orbitals iii. It has high electronegativity iv. It has high ionization enthalpy 19. Dinitrogen: Preparation •Commercial preparation – By the liquification & fractional distillation of air. •Laboratory preparation – By treating an aqueous solution NH4Cl with sodium nitrate. NH4Cl +NaNO2→N2 + 2H2O + NaCl •Thermal decomposition of ammonium dichromate also give N2. (NH4)2Cr2O7→ N2 +4H2O + Cr2O3 •Thermal decomposition of Barium or Sodium azide gives very pure N2. Properties: # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  3  sp hybridization, pyramidal shape 3  Pentahalides - sp d h...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) PROPERTIES 1. Ammonia is a colorless gas with pungent odour. 2. Highly soluble in water. 3. In solids & liquid states it exists as an associated molecule due to hydrogen bonding which accounts for high melting & boiling points of NH3 4. Trigonal Pyramidal shape NH3 molecule. 5. Aqueous solution of ammonia is weakly basic due to the formation of OH‐ ion. ZnSO4+ 2NH4OH→Zn (OH) 2+ (NH4)2SO4 6. Ammonia can form coordinate bonds by donating its lone on nitrogen, ammonia forms complexes. CuSO4+4NH3→ [Cu (NH3)4]2SO4 Name Nitrous oxide or Laughing gas Nitric oxide Dinitrogen trioxide Dinitrogen tetra oxide Dinitrogen pentaoxide # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Formula N2O NO N2O N2O4 N2O5 Oxidation state +1 +2 +3 +4 +5 Chemical nature Neutral Neutral Acidic Acidic Acidic Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change   PROPERTIES 1. Ammonia is a colorless gas with pungent odour....
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) PROPERTIES: ‐ (i) conc. HNO3 is a strong oxidizing agent & attacks most metals gold & Pt. (ii)Cr & Al do not dissolve HNO3 because of the formation of a positive film of oxide on the surface. (iii) It oxidises nonmetals like I2 to HNO3, C to CO2, S to H2SO4 (iv) Brown ring is used to detect NO‐. Phosphorus: a. It shows the property of catenation to maximum extent due to most stable P – P bond. b. It has many allotropes, the important ones are: i. White phosphorus ii. Red phosphorus iii. Black phosphorus White phosphorus Red phosphorus Black phosphorus Discrete tetrahedral P4 molecules Polymeric structure consisting of chains of P4 units linked together Exists in two forms - α black P and β black P Very reactive Less reactive than white P Glows in dark Very less reactive Does not glow in dark - Translucent waxy solid Has an iron grey luster Soluble in CS but insoluble in water Insoluble in water as well as CS2 It has low ignition temperature, therefore, kept under water - 2 # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Has an opaque monoclinic or rhombohedral crystals - Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  PROPERTIES       i  conc. HNO3 is a strong oxidizing agent   ...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) GROUP 16 ELEMENTS Group 16 Elements: O, S, SE, TE, PO General electronic configuration: ns2np4 Elements sulphur Se&Te Oxygen ATOMIC & PHYSICAL PROPERTIES Occurrence As sulphate such as gypsum CaSO4.2H2O,Epsom salt MgSO4.7H2O and sulphides Such as galena PbS,zinc blende ZnS,copper pyrites CuFeS2 As a decay product of thorium and uranium minerals. Comprises 20.946% by volume of the atmosphere. •Ionization enthalpy decreases from oxygen to polonium. •Oxygen atom has less negative electron gain enthalpy than S because of the compact nature of the oxygen atom. However from the S onwards the value again becomes less negative up to polonium. •Electronegativity gradually decreases from oxygen to polonium, metallic character increases from oxygen to polonium. •Oxygen & S are non‐metals, selenium and tellurium are metalloids.Po is a radioactive metal. •Oxygen is a diatomic gas while S, Se&Te are octa atomic S8, Se8&Te8 molecules which has puckered’ ring’ structure. CHEMICAL PROPERTIES Common oxidation state: ‐ ‐2, +2, +4 &+6. Due to inert effect, the stability of +6 decreases down the group and stability of +4 increases. Oxygen exhibits +1 state in O2F2, +2 in OF2. Anomalous behavior of oxygen‐due to its small size, high electronegativity and absence of d‐orbitals. TREND IN PROPERTIES Acidic character‐H2OH2S>H2Se>H2Te Reducing character‐H2SSeO2>TeO2 # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change   GROUP 16 ELEMENTS Group 16 Elements  O, S, SE, TE, PO Genera...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Stability of halides‐F>Cl>Br>I HALIDES DI HALIDES: sp3 hybridization but angular structure. TETRA HALIDES: sp3 hybridization‐see‐saw geometry HEXA HALIDES: sp3d2, octahedral SF6 DIOXYGEN Prepared by heating oxygen containing salts like chlorates,nitrares 2KClO3‐heat‐‐‐‐---------- 2KCl+3O2 22Fe3++SO2+2H2O----------2Fe2+ + SO4 + 4H+ 5SO2+2MnO4‐ +2H2O------------------5SO42-+4H+ +2Mn2+ SO2 molecule is angular. OXIDES A binary compound of oxygen with another element is called oxide. Oxides can be classified on the basis of nature •Acidic Oxides: ‐ Non metallic oxides. Aqueous solutions are acids. Neutralize bases to form salts.Ex:So2,Co2,N2O5 etc. •Basic Oxides: metallic oxides. Aqueous solutions are alkalis. Neutralize acids to form salts.Ex:Na2O,K2o, etc. •Amphoteric oxides: ‐some metallic oxides exhibit a dual behavior. Neutralize both acids & bases to form salts. Ex: ‐Al2O3,SbO2,SnO, etc…….. OZONE PREPARATION Prepared by subjecting cold, dry oxygen to silent electric discharge. 3O2→2O3 PROPERTIES Due to the ease with which it liberates atoms of nascent oxygen, it acts as a powerful oxidizing agent. For eg: ‐ it oxidises lead sulphide to lead sulphate and iodide ions to iodine. PbS+4O3→PbSO4+4O2 SULPHUR DIOXIDE PREPARATION Burning of S in air S+O2→SO2 Roasting of sulphide minerals # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Stability of halides   F Cl Br I HALIDES DI HALIDES  sp3 hybr...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) PROPERTIES 1. In aqueous solution it ionizes in 2 steps H2SO4+H2O----------H3O++HSO4HSO4‐+H2O---------H3O++SO422. It is a strong dehydrating agent Eg: ‐charring action of sugar C12H22 O11 +H2SO4---------------------- 12C+112O 3. It is a moderately strong oxidizing agent. Cu+2H2SO4(conc.) →CuSO4+SO2+2H2O C+2H2SO4 (conc.) →CO2+2SO2+2H2O GROUP 17 ELEMENTS (HALOGENS) Group 17 elsements: F, Cl, Br, I, At General electronic configuration: ns2np5 Element Occurrence Fluorine As insoluble fluorides(fluorspar CaF2,Cryolite and fluoroapattie) Cl, Br,I Sea water contain chloride bromide iodide of sodium, potassium, calcium but mainly sodium chloride solution (2.5% by mass). Certain forms of marine life(various seaweeds) ATOMIC AND PHYSICAL PROPERTIES i. ii. iii. iv. Atomic & ionic radii increase from fluorine to iodine. Ionization enthalpy gradually decreases from fluorine to iodine due to increase in atomic size. Electron gain enthalpy of fluorine is less than that of chlorine. It is due to small size of fluorine & repulsion between newly added electron &electrons already present in its small 2p orbital. Electronegativity decreases from fluorine to iodine. Fluorine is the most electronegative element in the periodic table. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  PROPERTIES 1. In aqueous solution it ionizes in 2 steps H2SO4...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) X X’n are called interhalogen compounds where n = 1, 3, 5, or 7 These are covalent compounds. All these are covalent compounds. Interhalogen compounds are more reactive than halogens because X-X’ is a more polar bond than X-X bond. All are diamagnetic. Their melting point is little higher than halogens. XX’ (CIF, BrF, BrCl, ICl, IBr, IF) (Linear shape) XX’3 (CIF3, BrF3, IF3, ICl3) (Bent T- shape) XX’5 – CIF5, BrF5, IF5, (square pyramidal shape) XX’7 – IF7 (Pentagonal bipyramidal shape) Oxoacids of halogens: Fluorine forms only one oxoacid HOF (Fluoric (I) acid or hypofluorous acid) due to high electronegativity. Acid strength: HOCl < HClO2 < HClO3 < HClO4 + - Reason: HClO4 → H + ClO4 most stable Acid strength: HOF > HOCl > HOBr > HOI This is because Fluorine is most electronegative. GROUP 18 ELEMENTS: Ionisation enthalpy: They have very high ionization enthalpy because of completely filled orbitals. Ionisation enthalpy decreases down the group because of increase in size. Atomic radii: Increases down the group because number of shells increases down the group. Electron gain enthalpy: They have large electron gain enthalpy because of stable electronic configuration. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  X X   n are called interhalogen compounds where n   1, 3, 5, ...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Melting and boiling point: Low melting and boiling point because only weak dispersion forces are present. XeF is linear, XeF is square planar and XeF is distorted octahedral. KrF is known but no true 2 4 compound of He Ne and Ar are known. 6 2 Compounds of Xe and F: Xe+F2+ 1bar, 675K⎯⎯⎯⎯⎯⎯→XeF2 Xe+2F2+873k, 7bar-----------------------XeF4 Xe+3F2+573k, 60-70bar------------------XeF6 XeF4+O2F6----------------XeF6+O2 XeF2, XeF4, XeF6 are powerful fluorinating agent Compounds of Xe and O: XeF4+12H2O------------4Xe+2XeO3+24HF+3O2 XeF6+3H2O-------------XeO3+6HF GROUP-15 IMPORTANT REASONING QUESTION 1. Nitrogen does not form pentahalide although it exhibit +5 oxidation state. Ans:-Due to absence d-orbitals N cannot extend its valences beyond four 2. PH3 has lower B.pt than NH3 # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Melting and boiling point  Low melting and boiling point beca...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-N is more electronegative than P so in NH3 there is intermolecular H-bonding hence it has high b.pt 3. NH3 acts as Lewis base Ans:-Because N has a lone pair electron so NH3 acts as a Lewis base 4. NO2 dimerises Ans:-NO2 has an odd electron so it dimerises to pair up electron and to achieve octet configuration 5. NH3 is stronger base than PH3 Ans:-Due to smaller size of nitrogen there is high electron density on nitrogen so electron pair is easily available. 6. PCl3 fumes in moisture Ans:-PCl3 undergoes hydrolysis and gives fumes of HCl. PCl3 + 3 H2O  H3PO3 + 3HCl 7. All the five P-Cl bonds are not equal in PCl5 Ans:-The two axial bonds suffer more repulsion from equatorial bonds and hence are elongated. 8. H3PO2 has reducing character Ans:-Since it has two P-H bonds 9. H3PO3 is dibasic (diprotic) but H3PO4 is tribasic Ans:-In H3PO3 only two H atoms are linked to O which are ionisable the third H is attached to P and not ionisable because P is less electronegative. In H3PO4 all the three H atoms are with O and ionisable 10. PCl5 is ionic in solid state Ans:-It is due to the following conversion: 2PCl5 ------ [PCl4] + [PCl6]11. NO is paramagnetic in gaseous state but diamagnetic in liquid and solid state Ans:-NO (g) has odd number of electrons so it is paramagnetic but in liquid and solid state it exists as dimmer so there is no unpaired electron and it will be diamagnetic 12. NCl3 hydrolyzed but NF3 does not Ans:-In NCl3 Cl has vacant d-orbitals to accept the lone pair from H2O but in NF3 F has no dorbitals NCl3 + 3H2O ---- NH3 + 3 HOCl # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -N is more electronegative than P so in NH3 there is inte...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 13. Nitrogen shows little catenation but phosphorous distinctly shows catenation property Ans:-Due to smaller size of N there is repulsion between the lone pairs and N-N single bond is weaker than P-P 14. +5 oxidation state of Bi is less stable than +3 ANS:-Because inert pair effect is very prominent in Bi, so +5 oxidation state is not stable 15. Bi in +5 oxidation state is strong oxidizing agent Ans:-Because inert pair effect is very prominent in Bi so Bi5+ can be easily converted into Bi3+ 16, NO (nitric oxide) becomes brown when released to air Ans:-It oxidizes to NO2 17. NH3 is a good complexing agent/ NH3 acts as a ligand Ans:-It has lone pair of electron on N-atom and can be donated for the coordination bond. 18.Bi2O3 is not acidic Ans:-The size of Bi3+ is very large and so there is very weak +ve electric field around it so it does not interact with water to release H+ 19. BiH3 is the strongest reducing agent among the group-15 hydrides Ans:-Since Bi-H bond is the weakest among pr-15 hydrides so H2 gas is evolved which is reducing 20. N2 is less reactive at room temperature Ans:-Due to having triple bond and hence high bond dissociation energy (946 kJ/mol) 21. Bond angle in PH4+ higher than in PH3 Ans:-In PH3 there is lp-bp repulsion so bond angle is less where as in PH4+ there is no lp-bp repulsion 22. NH3 has greater bond angle than PH3 Ans:-N is more electronegative so it attracts the bond pair electron and hence there is greater bpbp repulsion in NH3 and hence greater bond angle 23. R3P=O exists but R3N=O does not Ans:-N due to absence of d-orbitals cannot form pπ-dπ multiple bond 24. N exists as N2 but P exists as P4 # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  13. Nitrogen shows little catenation but phosphorous distinct...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-Due to smaller size N can form pπ-dπ multiple bonding and exists as discrete N2 molecule but P cannot form pπ-pπ multiple bonding. 25. PCl5 cannot act as reducing agent Ans:-In PCl5 P has +5 oxidation state. P has five valence electron in its valence shell so it cannot increase its oxidation state beyond +5, so it cannot act as reducing agent. 26. Phosphorous is kept under kerosene Ans:-It is highly reactive and easily catches fire due to air oxidation 27. H3PO3 is syrupy liquid Ans:-Due to intermolecular H-bonding 28. PH3 bubbles but NH3 dissolves in water Ans:-NH3 forms H-bonding with water but PH3 cannot form so NH3 dissolves but PH3 bubbles out 29. Only a small increase in radius is observed from As to Bi Ans:-Due to poor shielding effect of d and f orbitals. 30. Nitrogen is gas where as phosphorous is solid at room temp. Ans:-Nitrogen is diatomic molecule having weak van der Walls attraction where as phosphorous is tetra atomic so it has strong van der Walls attraction. 31. N-N bond is weaker than P-P bond Ans:-Due to shorter bond length there is greater repulsion between lone pairs in N2 32. Maximum number of covalent bond formed by N is four Ans:-Because it has three unpaired electrons and one lone pair. 33. P2O5 cannot be used for drying ammonia gas. Ans;-P2O5 is acidic it reacts with ammonia in presence of moisture and form (NH4)3PO4 34. NO2 is colored but its dimmer N2O4 is colorless Ans:-Because NO2 has unpaired electron so it can absorb light from VR 35. Acidity of oxyacids of nitrogen increases with increase in oxidation number of N Ans:-Because nonmetallic character increases with oxidation number 36. White phosphorous is more reactive than red phosphorous # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -Due to smaller size N can form p  -d   multiple bonding ...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-White phosphorous consists of discrete P4 molecules which is tetrahedral so reactive but in red phosphorous the P4 molecules are linked in extended chain structure so it is less reactive. 37. Phosphonic acid (H3PO4) is mono basic / mono protic Ans:-Only one H atom is linked with O which is ionisable 38. N2 has higher bond dissociation energy than NO Ans:-Because N2 has higher bond order 39. N2 and CO have same bond order but CO is more reactive Ans:-CO is polar molecule 40. (CH3)3N is pyramidal but (SiH3)3N is planar Ans:-(CH3)3N is pyramidal due to sp3 hybridization and one lone pair on N but (SiH3)3N is planar due to sp2 hybridization and its lone pair is donated to vacant d orbital of Si for pπ-dπ overlap 41. The first IE of N is greater than that of O Ans:-It is due to half-filled and hence stable electronic configuration of N 42. HNO2 disproportionate Ans:-In HNO2 the N is in +3 oxidation state which may increase as well as decrease 43. PCl5 cannot act as reducing agent Ans:-In PCl5 phosphorous is in +5 oxidation state that is the highest oxidation state of P. GROUP-16 1. Group 16 elements have lower I.E with compare to corresponding group 15 elements Ans:-Because group 15 elements have stable half-filled p-sub shell (ns2np3) so electron cannot be removed easily 2. H2S is less acidic than H2Te Ans:-In H2Te there is lower bond energy of H-Te bond due to larger size of Te 3. H2S acts as reducing agent while SO2 acts as both Ans:-In H2S , S has its minimum oxidation state -2 where as in SO2 it is +4 so it can be decreased up to -2 or increased up to +6 , So H2S is only reducing but SO2 is both. 4. H2S is acidic while H2O is neutral # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -White phosphorous consists of discrete P4 molecules whic...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-H-S bond is weaker due to larger size of S so proton release easier in H2S 5. SF6 is known but SH6 does not exist Ans:-Fluorine is the strongest oxidizing agent so it can oxidizes S to its maximum oxidation state +6, H can not 6. Compound of F & O is fluoride of oxygen not oxide of fluorine Ans:-F is more electronegative than O 7. SCl6 is not known but SF6 is known Ans:-F is strongest oxidizing agent so it can oxidizes S to its maximum oxidation state +6. Cl cannot. Again Cl has larger size so steric repulsion is there in SCl6 8. SF6 is used as gaseous electrical insulator Ans:-It is thermally stable and chemically inert 9. SF6 is not easily hydrolyzed Ans:-It is sterically protected by six F atoms hence does not allow H2O molecules to attack the S atom 10. S exhibits catenation properties but not Se Ans:-Due to smaller size of S than Se. S-S bond is much stronger than Se-Se bond 11. S disappears when boiled with Na2SO3 Ans:-It forms sodium thiosulphate. Na2SO3 + S  Na2S2O3 (soluble) 12. H2O is liquid but H2S is gas Ans:-O is electronegative so there is intermolecular H-bonding in water so it is liquid. 13. Ozone is powerful oxidizing agent Ans:-It decomposes to form nascent oxygen 14. Ka2 is less than Ka1, for H2SO4 in water Ans:-The 2nd proton releases from HSO4- which is difficult. So Ka2 is less than Ka1 15. O2 is gas but sulphur is solid Ans:-Due to smaller size O can form pπ-pπ multiple bond and exists as discrete diatomic molecule. 16. Group 16 elements are called chalcogens # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -H-S bond is weaker due to larger size of S so proton rel...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-Chalcogen means ore forming elements. They form several ores 17. Positive oxidation states of O are generally not found Ans:-Due to high electro negativity of O 18. Thermal stability decreases from H2O to H2Te in group 16` Ans:-Due to increase in atomic size from O to Te the bond dissociation energy decreases 19. O does not show +4 & +6 oxidation states like S Ans:-Due to absence of d-orbital in oxygen 20. The magnitude of electron gain enthalpy of oxygen is less than that of sulphur Ans:-Due to very small size of O there is inter electronic repulsion 21. Among the hydrides of group 16 water shows unusual properties Ans:-Due to H-bonding in water the molecules get associated 22. S exhibits catenation but not O Ans:-Because S-S bond is stronger than O-O bond 23. Tendency to show -2 oxidation state diminishes from O to Po in group 16 Ans:-Due to decreases in electronegativity moving down the group 24. O2 is paramagnetic although it has even number of electrons Ans:-Due presence of unpaired electrons in anti-bonding molecular orbitals 25. Sulphur in vapour state exhibit paramagnetism Ans:-In vapour stare sulphur partly exists as S2 molecule and like O2 it has unpaired electrons in π* orbitals 26. SF6 is less reactive than SF4 Ans:-In SF6 sulphur atom is sterically hindered due to six F atoms GROUP-17 1. Halogens have maximum negative electron gain enthalpy (ΔH) Ans:-Because they have smallest size in their respective periods # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -Chalcogen means ore forming elements. They form several ...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 2. F has less electron gain enthalpy than that of Cl but fluorine is stronger oxidizing agent than chlorine Ans:-F has very small size so there is interelectronic repulsion. F is stronger oxidizing agent due to its low bond dissociation energy and high hydration energy 3. F exhibits only -1 oxidation state, other halogen shows +1, +3, +5, +7 oxidation states Ans:-F is most electronegative element and due to absence of d-orbitals it cannot expand its octet so it does not exhibit positive oxidation state. 4. Iron reacts with HCl gives Fe (II) chloride and not Fe (III) chloride Ans:-Fe + 2 HCl  FeCl2 + H2 H2 liberated prevents the oxidation of FeCl2 to FeCl3 5. Bond dissociation energy of F2 is less than Cl2 Ans:-Due to very small size of F there is interelectronic repulsion in F2 so it has low bond dissociation energy 6. Fluorine does not undergo disproportionation Ans:-Disproportionation means simultaneous oxidation-reduction. electronegative element undergoes only reduction but not oxidation. F being the most 7. NO dimerises but Cl2O does not Ans:-NO is odd electron species so it complete its octet by dimerisation 8. Bleaching by Cl2 is permanent but by SO2 is temporary Ans:-Cl2 bleaches by oxidation while SO2 does it by reduction. The reduced product gets oxidized again in air and the colour returns 9. HF has lower acid strength than HI Ans:-Due to larger size of I, the H-I bond is weaker than H-F bond so HI is stronger 10. I2 is more soluble in KI than in water Ans:-I2 forms complex with KI i.e. K+I311. HClO is stronger acid than HIO Ans:-ClO- is more stable than IO- because Cl is more electronegative, so HClO is stronger 12. HClO4 is stronger acid than HClO3 Ans:-ClO4- is more stable than ClO3- due to more resonance # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  2. F has less electron gain enthalpy than that of Cl but fluo...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 13. OF2 should be called fluoride of oxygen and not oxide of fluorine Ans:-Because F is more electronegative than O 14. Interhalogens are more reactive than halogens Ans:-They are polar 15. HF is stored in wax coated glass bottle Ans:-HF reacts with alkali present in glass. 16. MF is more ionic than MCl ( M is alkali metal) Ans:-Because F- is smaller than Cl- and hence it is less polarizable. 17. Cl2 + KI  brown, but excess Cl2 turns it colorless 18. HClO4 is stronger than H2SO4 Ans:-Because the conjugate base ClO4- is stable due to resonance 19. ClF3 exists but FCl3 does not Ans:-F is smaller in size and cannot accommodate three chloride ions due to steric factor. 20. HF is less volatile than HCl Ans:-In HF there is intermolecular H-bonding so the HF molecules get associated 21. F form only one Oxo acid, HOF Ans:-Due to absence of d-orbital it cannot exhibit higher oxidation states 22. O form hydrogen bonding, Cl does not Ans;-O is more electronegative and small in size than Cl 23. Halogens are colored Ans:-Due to absorption of radiation from Visible rays 24. Iodine forms I3- but fluorine does not form F3Ans:-Due to small size of fluorine 25. HI cannot be prepared by heating KI with conc. H2SO4 26. The magnitude of electron gain enthalpy of F is less than that of Cl Ans:-Due to very small size of F there is inter electronic repulsion. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  13. OF2 should be called fluoride of oxygen and not oxide of ...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) 27. Fluorine is stronger oxidizing agent than chlorine though it has lower electron gain enthalpy Ans;-Fluorine has higher reduction potential value due to its low bond dissociation energy and high hydration energy with compare to chlorine. 28. Acid strength increases in the order HF< HCl < HBr < HI Ans:-As size increases from F to Cl the bond dissociation energy decreases from HF to HI GROUP-18 1. He, Ne do not form compound with F Ans;-Due to high IE 2. Noble gases have very low b.pt Ans:-Because there is only weak dispersion force between their atoms. 3. Hydrolysis of XeF6 is not a redox reaction Ans:-Because in the products formed XeOF4 and XeO2F2 the Xe has the same oxidation state (+6) as in XeF6 4. Ne used as warning signal Ans:-Because Ne – light has high fog penetration power 5. Noble gases form compounds only with fluorine and oxygen Ans:-Because F & O are the most electronegative elements 6. Xe does not form XeF3 or XeF5 Ans:-Xe has all paired electrons so promotion of one, two or three electrons will give rise to two, four or six unpaired electrons hence cannot form XeF3 and XeF5 7. Out of noble gases only Xe forms compounds Ans:-Because Xe has comparatively low IE and vacant orbitals for promotion of electrons 8. Noble gases are mostly inert Ans:-Because they have completely filled valence orbitals i.e octet configuration 9. He is used as diving apparatus Ans:-Because it is less soluble in blood with compare to nitrogen 10. It is difficult to study the chemistry of Rn # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  27. Fluorine is stronger oxidizing agent than chlorine though...
B RAINBOX EDUCATION (Imparting Knowledge, Inspiring Change) Ans:-Because Rn is radioactive and hence very unstable 11. Noble gases have comparatively large atomic size Ans:-They are mono atomic so their van der Walls radii measured which is longer than covalent/ionic or metallic radii. # SCF-5, Near Abiss, Rishi Nagar Market, Ludhiana (141001). Email ID: brainboxeducation.ldh@gmail.com Contact: +91-89689-54535 +91- 81469-50515
B  RAINBOX EDUCATION  Imparting Knowledge, Inspiring Change  Ans -Because Rn is radioactive and hence very unstable 11. No...