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Chemistry of P-Block Elements

Chemistry of P-Block Elements. Proff. Kale Ganesh. Khanderao. Proff. Borawake Ganesh.Anilrao. Department of Chemistry Jijamata College of Science and Arts, Bhende bk. The Periodic Table of the Elements. H. He. Elements that are polyatomic in their natural state. Li. Be. B. C.

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Chemistry of P-Block Elements

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  1. Chemistry of P-Block Elements Proff. Kale Ganesh. Khanderao. Proff. Borawake Ganesh.Anilrao Department of Chemistry Jijamata College of Science and Arts, Bhende bk.

  2. The Periodic Table of the Elements H He Elements that are polyatomic in their natural state Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Sb Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Diatomic Octatomic ( 8 atoms per molecule) Tetratomic ( 4 atoms per molecule)

  3. Electron Affinity Ionization Potential Atomic Size Non Metallic Character Electron Affinity Metallic Character Ionization Potential Atomic Size

  4. Introduction • The long form of periodic table has – • Left-hand Portion Of • S-block Element (Gr. IA & IIA). • Right-hand Portion Is • P-block Element (Gr. IIIA To VIIA), • Inert gases (Gr. VIIIA) • Middle Portion Consists Of • Transition (d-block) • Inner transition (f-block) elements • (Gr. IB To VIIIA).

  5. P-BLOCK The elements consists of the last six groups minus helium (which is located in the s-block). In the elemental form of the p-block elements, the highest energy electron occupies a p-orbital. The p-block contains all of the nonmetals (except for Hydrogen and Helium which are in the s-block) and semimetals, as well as some of the metals. The groups of the p-block are: 13 (IIIB,IIIA): Boron Group 14 (IVB,IVA): Carbon Group 15 (VB,VA): Nitrogen Group 16 (VIB,VIA): Chalcogens 17 (VIIB,VIIA): Halogens 18 (Group 0): Noble gases (excluding Helium)

  6. Chemistry of Group IIIA Boron Family

  7. Group IIIA – Boron Family The Gr.IIIA contains elements Boron (5B), Aluminium (13Al), Gallium (31Ga), Indium (49In), Thallium (81Tl). In these elements have three electrons in their outer orbital. Their electron configuration is ns2, np1. Anomalous behavior of Boron – Boron is the first element of Gr. IIIA. The element Boron is differs in its behaviors from other member of Gr.IIIA, but it resembles the next period element i.e. Silicon. This is called as Diagonal relationship. Boron differs due to its small size, high electro negativity & absence of d-orbital. Difference in properties: - 1. Boron is non-metal; other elements of Gr.IIIA are metals. 2. Oxides – B2O3 is Acidic; Al2O3 & Ga2O3 are Amphoteric while In2O3 & Tl2O3 are basic. 3. Boron halides are monomeric & covalent e.g. BCl3; while other halides of Gr. IIIA are dimeric e.g. Al2Cl6. 4. Boron hydroxides are acidic; while hydroxides of other elements are amphoteric or basic. 5. Boron extend its coordination no. beyond 4 due to absence of d-orbital; while other elements can extends their coordination no. upto 6.

  8. Group IIIA – Boron Family Their position in periodic table is in Gr. IIIA -13. In these elements have three electrons in their outer orbital. So their electron configuration is ns2, np1.

  9. Trends in Properties 1) Size of atoms & ions: As we go from top to bottom in Group i.e. from B to Tl, atomic & ionic size increases. Although nuclear charge increases, the addition of new shell is more effective & size increases steadily from B to Tl. The atomic size increases from B to Al is 0.80 Å to 1.25 Å, but from Al to Tl size increase is very small i.e. Ga -1.25 Å, In – 1.50 Å & Tl –1.55 Å. If trivalent ions are consider, the ionic radii of elements increases from B to Tl i.e. B – 0.20 Å, Al – 0.50 Å, Ga – 0.62 Å, In – 0.82 Å, Tl – 0.95 Å,

  10. Trends in Properties 2) Ionization Potential: - The Gr. IIIA elements have two s-orbital & one p-orbital electron. The p-electrons are away from nucleus compare to s-electron. Thus they held less tightly than s-electron. So first I.P. of these elements are low. The second & third I.P. are considerably higher. In Gr. The I.P. gradually decreases from top to bottom. The I.P. value of depends on atomic size, nuclear charge & screening effect. Boron has highest I.P. i.e. 8.3 eV, due to smallest size, Al has 5.98 eV due to increasing in size. The I.P. of Ga is more than Al i.e. 6.0 eV because of introduction of d- orbital electrons. In has 5.79 eV & Tl has 6.11 eV I.P. value.

  11. Trends in Properties 3) Electro negativity: - It is the power of atom to attract electrons to itself. The electro negativity decreases from B (2.04) to Al (1.60), due to increase in size. However Ga (1.81) shows slight increase, which is unexpected. The remaining two elements shows slight decrease i.e. In (1.78) & Tl (1.62). Thus the electro-negativity value does not fall as expected due to presence of extra d-electron & f-electron.

  12. Trends in Properties 4) Oxidation states: - General electron configuration of Gr. IIIA elements is ns2, np1. This shows +III oxidation state, while Tl shows +I, which is most stable. These elements forms trivalent covalent compounds e.g. AlCl3, GaCl3, etc. The stability of +III O.S. decreases from B to Tl, stability of +I O.S. increases from B to Tl. This is due to increases in atomic size. The Ga & In shows +II O.S. e.g. Ga [GaCl4]- * B & Al shows stable oxidation state +III, * Ga & In shows stable oxidation state +I & +III, * Tl shows stable oxidation state +I.

  13. Trends in Properties 5) Reactivity: - These elements have slightly higher Ionization Potential than alkaline earth metals. So Gr. IIIA elements are less reactive. They shows tendency to form covalent compound. Amorphous Boron is reactive; it burns in air to form oxides B2O3, nitrides BN & halogens BX3. While crystalline Boron is unreactive. Aluminum is stable in air because it forms stable oxide film, but in absence of film metal is rapidly oxidizes & decomposes water. Indium & Gallium are stable in air & not attack by water. Thallium is more reactive & oxidizes in air.

  14. Bonding & shapesDialuminium Hexabromide (Al2Br6) Al undergoes SP3 hybridization using one S & three P orbitals. Three SP3 hybrid orbitals contain only one electron, while fourth hybrid orbital is empty. These four SP3 hybrid orbital are directed to corners of tetrahedron. Aluminium bromide exists in diamer. The fourth empty SP3 hybrid orbital of Al receives an electron pair by co-ordinate bond from Br of second molecule. Thus in Al2Br6, each Al completes its octet by forming three covalent & one co-ordinate bond with bromine. The shape of molecule is roughly tetrahedral. The dimmer is breaks into monomer (AlBr3) at very high temperature i.e. in vapour state.

  15. Bonding & shapesDialuminium Hexabromide By far the most common form of aluminium bromide is Al2Br6. This species exists as hygroscopic, colorless, solid at standard conditions. Typical impure samples are yellowish or even red-brown. It is prepared by the reaction of HBr with Al: 2 Al + 6 HBr → Al2Br6 + 3 H2 Alternatively, the direct bromination occurs also: 2 Al + 3 Br2 → Al2Br6

  16. Bonding & shapesDialuminium Hexabromide

  17. Chemistry of Group IVA Carbon Family

  18. Group IVA (14) – Carbon family The Gr.IVA contains elements Carbon (6C), Silicon (14Si), Germanium (32Ge), Tin (50Sn), Lead (82Pb). In these elements have four electrons in their outer orbital. General electron configuration is ns2, np2. C & Si are non-metals; Ge is metalloids while Sn & Pb are metals. Anomalous behavior of Carbon – Carbon is the first element of Gr. IVA. The element Carbon is differs in its behaviors from Si, Ge, Sn, and Pb of Gr.IVA. Carbon differs due to its small size, high electro negativity & absence of d-orbital.

  19. Carbon Family Difference in properties: - 1. Carbon has unique ability to form multiple bond e.g. C=C, C= C, C=O, C=N, C=S. while other elements of this Gr. Forms only single bond. 2. Carbon has special ability to form long chain compounds i.e. High Catenation. 3. Carbon tetra halide (CCl4) do not undergo hydrolysis, while other halides undergoes hydrolysis reaction. 4. Carbon extend its coordination no. beyond 4 due to absence of d-orbital; while other elements can extends their coordination no. upto 5, 6 or even beyond by using d-orbital.

  20. Group IVA – Carbon Family Their position in periodic table is in Gr. IVA -14. In these elements have four electrons in their outer orbital. So their electron configuration is ns2, np2.

  21. Trends in Properties 1) Size of atoms & ions: The size of atoms & ions goes on increasing from top to bottom. As we go from top to bottom in Group i.e. from C to Pb, atomic & ionic size increases. Although nuclear charge increases, the addition of new shell is more effective & size increases steadily from C to Pb. Atomic size increases from C to Si is 0.77Å to 1.17Å, but from Si to Ge size increase is very small due to screening effect with introduction of d-orbital electron. i.e. Ge -1.22Å, Sn –1.41Å, while in Pb –1.45Å due to presence of f-orbital. If tetravalent ions are consider, the ionic radii of elements increases from C to Pb i.e. C –0.16Å, Si –0.42Å, Ge –0.53Å, Sn –0.71Å, & Pb –0.84Å. Due to small size carbon & silicon have very high M.P. & B.P. i.e. C – M.P.3930ºC, B.P.4200ºC & Si –M.P. 1410ºC, B.P.3680ºC. while larger metals like Ge, Sn, Pb have lower M.P. & B.P.

  22. Trends in Properties

  23. Trends in Properties 2) Ionization Potential: - The outermost electrons are held more tightly by nucleus of atom. So more energy is required to remove them. Hence I.P. of Gr. IVA elements are more than that of Gr. IIIA elements. The Gr. IVA has two s-orbital & two p-orbital electrons. The I.P. decreases from C (11.2 eV) to Si (8.10 eV) due to increase in size. However the change is irregular from Ge (8.09 eV), Sn (7.30 eV), & Pb (7.38 eV). This is due to filling of d-electrons & f-electron. The large amount of energy is required to form M+4 ions. Thus the formation of ionic compounds is very difficult. Generally they form covalent compounds.

  24. Trends in Properties 3) Electro negativity: - It is the power of atom to attract electrons to itself. The carbon is most electronegative element in the group IVA. The electro negativity decreases from C (2.55) to Si (1.90), due to increase in size. There after the electronegativity practically remains same for Ge (2.01), Sn (1.80), Pb (1.81), because presence of extra d-electron & f-electron showing ineffective screening & thus increase in nuclear charge.

  25. Trends in Properties 4) Oxidation States: - General electron configuration of Gr. IVA elements is ns2, np2. This shows four electrons in valence shell. For stability these elements either to loose or gain four electrons. The energy to add or to remove four electrons is very high, thus the formation of M+4 is very difficult or not possible. The element shows +IV O.S. through covalence with halogen, sulphur or oxygen, etc. The stability of +IV O.S. decreases from C to Pb. The tetravalent compounds of carbon are most stable, while corresponding compounds of lead are least stable. These elements shows +IV O.S. with more electronegative elements e.g. CCl4, SiCl4, while it shows –IV O.S. with more electropositive elements, e.g. Be2C, Na4C. Some of these shows +II O.S. The stability of +II O.S. increases from C to Pb, e.g. GeCl2, SnCl2, PbO, PbCl2. * C & Si shows stable O.S. +IV, * Ge & Sn shows stable O.S. +II & +IV, * Pb shows stable O.S. +II.

  26. Trends in Properties 5) Reactivity: - The elements of these Groups are relatively unreactive. Chemical reactivity increases from C to Pb, but Lead is less reactive than Tin. All these elements react with halogen to form halides like CCl4, SiCl4, SnCl4, and SnCl2. To form oxides like CO2, SiO2, PbO2, etc when reacts with Oxygen. These elements are attacked by strong acids & strong bases. Only Tin is dissolve in Dilute acid producing hydrogen leaving Sn (+II) in solution. Sn + 2HCl SnCl2 + H2 Gas

  27. Bonding & shapes of Molecules Carbon dioxide (CO2) Electron configuration of C (6) –1S2, 2S2, 2P2 The Carbon Dioxide is triatomic molecule with linear shapes. In CO2, carbon is tetravalent & oxygen is divalent atom. Out of four orbital of Carbon one S & one P orbital are hybridized to form SP hybrid orbital, lie in straight line making 180º. Two hybrid SP orbital overlaps with p-orbital of two oxygen atoms forming two SP-P sigma (s) bond. The unhybridised two p-orbital of carbon overlaps sidewise (laterally) with P- orbital of oxygen atom, forming pi (p) bond. Thus CO2 molecule is linear with double bond between C & O atom. It shows that in CO2, there are two s & two p bonds. σσ Thus CO2 molecule is O = C = O ΠΠ The CO2 molecule is monomeric. The dipole moment of CO2 molecule is zero. This suggests molecule have linear geometry. C – O bond distance is 1.15Å, which is intermediate between those for C = O is 1.22Å & C = O is 1.10Å

  28. allotropes of carbon Eight allotropes of carbon: a) Diamond, b) Graphite, c) Lonsdaleite, d) C60 (Buckminsterfullerene or buckyball), e) C540, f) C70, g) Amorphous carbon, h) single-walled carbon nanotube or buckytube.

  29. Bonding & shapes of Molecules 2. Diamond & Graphite: - Carbon exists in allotropic forms like diamond, graphite, charcoal, lampblack, cock, amorphous carbon, etc. Diamond -Each carbon atom shows SP3 hybridization & it is joined to four other carbon atoms by Tetrahedral. This form is 3-D structure. The C- C bond length is 1.54 Å. The bond between C- C is very strong & stable. Therefore, diamond is very hard with high M.P. (3900 ºc). The density is also very high (3.51 g. /ml.). All electrons are involves in bonding thus diamond is bad conductor to heat & electricity. Graphite - Each carbon atom SP2 hybridization. This gives 2-D structure. The bond C- C bond length is 1.42 Å. & distance between two layers is 3.35 Å. The parallel layers are loosely bonded by weak Van- deer-Waal’s force, due to this reasons graphite is becomes soft & used for lubricating purpose. Its density is low (2.25g. /ml.). Each carbon has one unused electron in P-orbital; hence the graphite has good thermal & electrical conductor. It is used in making electrodes & carbon arc, in making lead pencil, etc.

  30. Bonding & shapes of Molecules 3. Fullerene C60: - It is new form i.e. allotrope of carbon. This C60 was discovered recently in 1985 by KROTO (U. K.), CURL & SMALLEY (U.S.). For the discovery of Fullerene, they got Noble prize in Chemistry (1996). It was named as FULLERENE in the honors of American Architect BUCKMINISTER FULLER. When electric spark is struck between graphite electrodes, then soot is produce. This soot consists of small amount of C60 & carbon black. This Fullerene has 32 faces with 12 pentagons & 20 hexagons. All carbon atoms are equivalent. Due to this symmetrical structure is very stable & hence inert. The cavity within a molecule is very large, about 7 Å in diameter. The average 6:6 & 6:5 bond lengths are 1.391 Å. & 1.444 Å. The structure looks like soccer ball & thus some time called as Bucky ball. Fullerene can be used as catalyst as well as in organometallic chemistry. In future it may used as powerful lubricant due to softness; but as its size reduced about 30%, it becomes harder than Diamond & easily cuts diamonds.

  31. Chemistry of Group VA Nitrogen Family

  32. Group VA(15) – Nitrogen Family The Gr.VA contains elements Nitrogen (7N), Phosphorous (15P), Arsenic (33As), Antimony (51Sb) & Bismuth (83Bi) is termed as Nitrogen family elements. These elements have five electrons in their outer orbital. So their electron configuration is ns2, np3. Anomalous behavior of Nitrogen – Nitrogen is the first element of Gr. VA, which differs from rest of elements of these Gr. due to its small size, high electro negativity, absence of d-orbital & high Ionization Potential.

  33. Group VA(15) – Nitrogen Family Difference in properties: - 1. Nitrogen extend its coordination no. beyond 4 due to absence of d-orbital e.g.NH4Cl, while other elements can extends their coordination no. more than 4 e.g. PCl5, PCl6. 2. At room temperature nitrogen exists in diatomic gas contain triple bonds between two nitrogen i.e. N=N, but at R.T. other elements are solid & exists as poly atomic molecule with single bond, e.g. P4 or as single molecule as Bi. 3. Due to triple bond, nitrogen molecule is unreactive, while all other elements of this group are reactive. 4. Nitrogen shows oxidation state from –III to +V, while other show either +III or +V O.S. 5. Nitrogen hydride (Ammonia-NH3) is stable & basic. While hydrides of other elements do not shows basic properties. 6. Only Nitrogen form H- bond while other not forms.

  34. NITROGEN PHOSPHOROUS ARSENIC ANTIMONY BISMUTH

  35. Trends in Properties 1) Size of atoms & ions: As we go from top to bottom in Group i.e. from N to Bi, atomic & ionic size increases. Although nuclear charge increases from N to Bi, the addition of new shell is more effective & atomic & ionic size increases steadily. Atomic size increases from N (0.80Å), P (1.25Å). This increase is very large, but small increase in As (1.21Å) due to screening effect & addition of d-electron. So again increase in size for Sb (1.41Å), while at Bi(1.52Å) increase due to f-electron introduction. If the ionic radius of M+5 (pentavalent) ions are consider, the ionic radii of elements increases from N to Bi i.e. M+3 N–1.71Å; M+5, P– 0.34Å, As – 0.47Å, Sb– 0.62Å, Bi– 0.74Å,

  36. Trends in Properties 2) Ionization Potential: - The I.P. of Gr. VA elements are more than that of Gr. IV. This is due to smaller size than those of Gr. IV elements. These elements have special stability of half field P-orbital. So outer most electrons are held more tightly & more energy is requiring removing outermost electron. These elements do not form ionic compound, they forms only covalent compounds. These elements have five valence electrons (two s-orbital & three p-orbital electron). Extremely very large amount of energy is requiring to form M5+ ion, hence ionic compound containing M5+ is not possible. In Gr. The I.P. gradually decreases from top to bottom. It is depends on atomic size, nuclear charge, & screening effect. First I.P. are- N (14.48 eV), P (10.90 eV), As (9.81eV), Sb (8.64 eV), & Bi (7.29 eV).

  37. Trends in Properties 3) Electro negativity: - The elements of Gr. VA have more electronegativity than elements of Gr. IVA. The electronegativity decreases from N (3.04) to P (2.10), due to increase in size. However from P to Bi is very small due to presences of d & f electron; As (2.00), Sb (1.82), Bi (1.67). Due to more electronegativity first three elements i.e. N, P & As combines with electropositive alkali & alkaline earth meals to form Na3N, Mg3P2, Na3As; while Sb & Bi combine with electronegative elements like O & halogens to form Sb2O3, BiCl3, etc.

  38. Trends in Properties 4) Oxidation states: - These elements have five valence electron in atom. For stability the atom can either lose five electrons or gain three electrons i.e. M+5 or M3-. N & P atoms are gain three electrons to form M3- due to small size & high electronegative to form Na3N, Mg3P2, and Ca3P2. These elements can share three electrons & shows M3+. The stability of +V O.S. goes on decreasing, while stability of +III O.S. increases from top to bottom. Thus - III, +III & +V are common O .S. of Gr. VA. Nitrogen shows great variety in covalent O.S. e.g. NH3 (-III), N2H2 (-II), NH2OH (-I), N2 (0), N2O (+I), NO (+II), N2O3 (+III), NO2 (+IV), N2O5 (+V).

  39. Trends in Properties 5) Reactivity:- These elements have special ability of half field p-orbital. So these elements are less reactive. Triple bond energy of N2 molecule is very high (226 kcal/mol). So N2 molecule is inert. Phosphorous exists in white, red, & black allotropic form as tetra-atomic P4 molecule. It is highly reactive. Nitrogen reacts with Oxygen at 3000ºc; while white Phosphorous react with oxygen at R.T. Arsenic, Tin & Lead react with oxygen on heating.

  40. Bonding & shapes of Molecules 1. PHOSPHOROUS: It exists in three allotropic forms i.e. white, red, & black phosphorous. White Phosphorous is tetrahedral P4 molecule. In P4 each P atom is linked to other three atoms by P-orbital. White phosphorous is highly reactive (burns at R.T.). The Red Phosphorous obtained from white phosphorous by heating it in absence of air at 250ºc. It has polymeric form consists of chain of P4 tetrahedron join together. It is less volatile, less reactive & less soluble than white phosphorous. Black Phosphorous is obtained from white phosphorous by applying high pressure. It is least reactive. White Phosphorous Black Phosphorous Red Phosphorous

  41. White phosphorous reacts vigorously with the oxygen in air and must be stored under water. Red phosphorus is stable in air. Source: Stock Boston

  42. Bonding & shapes of Molecules 2. PHOSPHOROUS TRIOXIDE (P4O6) & PHOSPHOROUS PENTAOXIDE P4O10) : Phosphorous forms main two oxides i.e. trioxide (P4O6) & pentaoxide (P4O10). Both exits in dimers Electron configuration of P (15) –1S2, 2S2 , 2P6,3S2, 3P3, 3d0 In P4O6, each Phosphorous atom share its three 3P unpaired electron & each oxygen atom share its two 2P unpaired electrons. This forms single covalent bond between four phosphorous & six oxygen atoms. In P4O10, each Phosphorous atom share its three 3P unpaired electron & each oxygen atom share its two 2P unpaired electrons. This forms single covalent bond between four phosphorous & six oxygen atoms. Each phosphorous donates its 3S pair of electron to new oxygen atom to accommodate with two unpaired electron. This form coordinate bond between P-O. This is PΠ-dΠ bonding. Thus in P4O10, six oxygen atoms are joined by single bond & remaining four oxygen atoms joined by double bond to these four phosphorous atoms.

  43. PHOSPHOROUS TRIOXIDE (P4O6) & PHOSPHOROUS PENTAOXIDE P4O10)

  44. Chemistry of Group VIA Oxygen or Chalcogen Family

  45. Group VIA(16) – Oxygen Family Oxygen (8O), Sulphur (16S), Selenium (34Se), Tellurium (52Te) & Polonium (84Po) are termed as Chalcogens i.e. ore forming elements. The first four elements are nonmetals, while Polonium is metal & it is radioactive. These elements have six electrons in their outer orbital. So their electron configuration is ns2, np4. Anomalous behavior of Oxygen – Oxygen is the first element of Gr. VIA which differs from rest of elements of these Gr. due to its small size, high electro negativity, absence of d-orbital & high Ionization Potential.

  46. Group VIA(16) – Oxygen Family Difference in properties: - 1. Oxygen cannot extend its coordination no. beyond 4 due to absence of d-orbital, while other elements can extends their coordination no. more than 4 e.g. SF6, SeF6. 2. At room temperature oxygen exists in diatomic gas contain double bonds between two oxygen i.e. O=O, but at R.T. other elements are solid. 3. Due to high electronegativity, oxygen atom shows H-bonding, most of its compounds are ionic, e.g. CaO, MgO; while other do not show H-bond & there compounds are covalent, e.g. SO2, SeO2. 4. Oxygen molecule is paramagnetic, while other elements are diamagnetic in nature. 5. Oxygen shows -II (rarely - I, e.g. H2O2) oxidation state, while other shows positive & higher Oxidation state, e.g. SF6, SeO3, TeO2.

  47. Trends in Properties 5) Reactivity:- These elements have special ability of half field p-orbital. So these elements are less reactive. Triple bond energy of N2 molecule is very high (226 kcal/mol). So N2 molecule is inert. Phosphorous exists in white, red, & black allotropic form as tetra-atomic P4 molecule. It is highly reactive. Nitrogen reacts with Oxygen at 3000ºc; while white Phosphorous react with oxygen at R.T. Arsenic, Tin & Lead react with oxygen on heating.

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