If I Have C in Class and I Take It Again and Result Is a
The d-cake of the Periodic Tabular array contains the elements of the groups 3-12 in which the d·orbitals are progressively filled. There are mainly three serial of the elements, 3d-series (Sc to Zn) 4d-series (Y to Cd) and 5d-series (La to Hg omitting Ce to Lu). The fourth 6d-series which begins with Ac is still incomplete.
Transition Elements
Elements having partially filled d-orbitals in ground state or in excited state, are known as transition elements. They have been placed in the centre of the Periodic Table between s-block and p-block elements.
Fe is the almost abundant and widely used transition metal.
General Electronic Configuration of Transition Elements
Transition elements have the electronic configuration (north – ane)d1 – ten nso – two, Zn, Cd, Hg, the end members of commencement iii series have general electronic configuration (northward – 1)d10ns2. These elements do not show properties of transition elements to any extent and are called non-typical transition elements.
Electronic Configuration of Transition Elements
Full general Concrete Backdrop of Transition Elements
(i) Atomic and ionic size Ions of the same charge in a given series exhibit regular decrease in radius with increasing atomic number, because the new electron enters in a d – orbital and nuclear accuse increases past unity.
In final of the series, a pocket-sized increase in size is observed due to electron-electron repulsion.
(Atomic and ionic radii increment from 3d-series to 4d-series but the radii of the third (Sd) serial elements are virtually the same equally those of the corresponding member of the second series. It can be explained on the basis of lanthanoid contraction [poor shielding of 4f ].
Due to lanthanide contraction Zr and Hf Have almost similar radii.
(ii) Ionisation enthalpies In a series equally nosotros motility from left to right, ionization enthalpy increases due to increase in nuclear charge but not in regular trend.
The irregular trend in the first ionisation enthalpy of the 3d metals, though of little chemic significance, can be accounted past considering that the removal of 1 electron alters the relative energies of 4s and 3d-orbitals.
(iii) Oxidation states Transition metals testify variable oxidation country due to 2 incomplete outermost shells. Only stable oxidation states of the first row transition metals are
Sc(+3) , Ti(+iv). Five(+5), Cr(+iii, +6), Mn(+2, +7), Iron(+2. +three). Co(+2, +3). Ni(+two), Cu(+2), Zn(+2).
The transition elements in their lower oxidation states (+2 and +3) commonly forms ionic compounds. In higher oxidation state compounds are normally covalent.
Only Bone and Ru testify +8 oxidation states in fluorides and oxides. Ni and Fe in Ni(CO)4 and Fe(CO)5 prove zero oxidation state.
(4) Enthalpy of atomisation Transition elements exhibit higher enthalpies of atomization. Considering of the presence of a big number of unpaired electrons in their atoms, they accept stronger interatomic interactions and hence, stronger bond.
(v) Trends in the Chiliadtwo+ / M standard electrode potentials
Eo M2+ / Grand is governed by iii factors. Enthalpy of sublimation, enthalpy of ionisation and enthalpy of hydration.
The irregular trend in 3d serial is due to irregular variation in ionisation enthalpy and oestrus of sublimation.
Except copper 3d – elements are proficient reducing agents.
[If sum of the first and second ionisation enthalpies is greater than hydration enthalpy standard potential (Eo Mii+ / G) volition be positive and reactivity volition be lower and vice-versa.]
(vi) Melting and boiling signal Due to strong metallic bond, they have high m.p. and b.p. The m.p. of these elements becomes maximum and then decreases with the increase in atomic number.
Manganese and technetium prove abnormal values in the tendency. Tungsten has the highest m.p. (3410oC).
Mercury is liquid at room temperature (thou.p. – 38.nine°C) due to absence of unpaired electrons, and weak metallic bonding.
(vii) Density d-block elements have high density because of their small diminutive size and strong metallic bonding.
Osmium has slightly lower density (22.52 g cm-3) equally compared to iridium (22.61 m cm-2). Thus, iridium has the highest density among transition metals.
(viii) Diminutive book Atomic volume decreases along the period due to decrease in diminutive size.
(nine) Reactivity d-block elements are less reactive due to high ionisation energies. Some are well-nigh inert and known every bit noble metals, east.yard., Au; Pt, Os, Ir, etc
(xii) Complex formation They are well known to form a big number of complex compounds mainly due to
(a) small atomic size and high nuclear charge
(b) presence of partly filled or vacant d-orbitals, e.1000.,K4[Atomic number 26(CN)6]
(thirteen) Coloured ions Colour exhibited by transition metal ions is due to the presence of unpaired electrons in d-orbitals and is due to the d-d transitions of electrons, when invisible lite is incident on the ion.
Color of a complex depends on the metal, its oxidation country and its ligands, e.g., [Cu(HiiO)iv]2+ is stake blue while [Cu(NH3)four]2+ is night blue. CuSO4· 5HtwoO is blue in colour and anhydrous CuSO4 is colourless.
Charge transfer likewise give intense colour due east.grand., MnO– four ion does not contain any unpaired d-electron. Its purple color is due to charge transfer from O to Doctor, thus O-ii alter to O– and Mn(VII) to Mn(Vl). Charge transfer is possible only when the energy levels on the two different atoms involved are adequately close.
(14) Magnetic properties
(a) Paramagnetic nature is due to the presence of unpaired electrons in d-orbitals. Paramagnetic graphic symbol increases with increment in the number of unpaired electrons and highest for Mn(2) [among 3d-series].
(b) Diamagnetic substances are repelled past applied magnetic field and have no unpaired electron.
(c) In ferromagnetism, permanent magnetic grapheme is acquired by substance due east.thousand., Fe.
Magnetic moment is given past
μ = √n (n + 2) BM,
Where, northward = number of unpaired electrons and BM = Bohr magneton (unit of magnetic moment).
(fifteen) Catalytic properties The transition metals anti their compounds behave like goad due to
(a) the presence of partly filled d-orbitals resulting in variable oxidation states.
(b) formation of intermediate complex with reactants by lowering the energy of activation.
(c) their rough expanse which provides active sites for adsorption of reactant molecules.
Iron in the preparation of NHiii (Haber's process), finely divided nickel for hydrogenation, Pt in the preparation of nitric acrid (Ostwald's process)
Some important catalysts having transition metals are
ane. Ziegler Natta catalyst : TiCI4 + (C2H5)three AI
2. Lindlar's catalyst : Pd / BaSOiv
iii. Wilkinson'due south goad : [Ph3PthreeRhCI
4. Adam's catalyst : Pt / PtO
5. Brown'southward catalyst or P-2 catalyst: Nickel boride
(fourteen) Formation of alloys d-block elements have a potent trend to class alloys, because their diminutive :;ires are Vel')' similar and in the crystal lattice i metal can be readily replaced past some other. Alloys so formed have high m.p.. The metals Mo, W, Cr, Ni, and 5 are used for the production of stainless steel.
Amalgam is an alloy formed past mercury with other metals, Iron and platinum do not grade any blend with mercury.
List of Alloys
(xv) Interstitial compounds The vacant space present in a crystal lattice is known as interstitial site or void. The not-metal atoms (e.g., H, Northward, C, etc.) due to their pocket-size size when occupy such place, the resulting compound is known every bit interstitial compound. Such compounds are hard and rigid, due east.g., cast iron and steel.
(xvi) Non-stoichiometric compounds The compounds not navm the elements in the exact ratio as in the ideal crystal are known non-stoichiometric compounds e.thousand., in Fe0.94Oi the Fe : O is approx 0.94 : 1 and not exactly ane : ane. It is due to the variability of Oxidation state in the transition element. These elements grade such compound by trapping H, B, C and N etc.
(xvii) Spinel These are the mixed oxides in which oxygen atoms constitute a fcc lattice e.chiliad., ZnFe2O4 It is a normal spinel in which the trivalent ions occupy the octahedral holes and divalent ions occupy the tetrahedral holes.
In inverse spinel, the trivalent ion occupy the tetrahedral holes and divalent ion occupy the octahedral holes. due east.g., FeFe2O4 or Atomic number 26iiiOfour.
Some of import reagents having transition metals
1. Baeyer'due south reagent Dilute alkaline KMnO4 used to exam the presence of unsaturation.
ii. Tollen's reagent Ammoniacal solution of AgNO3, i.e., [Ag(NH3)2]OH. used to exam the aldehyde group.
iii. Nessler's reagent Alkaline solution of Thou2HgI43 (m) and NH: .
four. Bridegroom'southward solution CuSO4 solution + sodium citrate + NaiiCO3, used to test the aldehyde group.
5.Lucas reagent HCl (cone.) + anhydrous ZnCltwo, used to distinguish between 1°, 2° and iii° alcohols.
Applications of transition elements
1. A mixture of TiOii and BaSO4 is chosen titanox and a mixture of ZnS + BaSO4 is called lithopone.
2. TiCI2 and TiO2 are used in smoke screens. TiOtwo is as well used as white pigment of paints.
iii. Tantalum is used in surgical venables and analytical weights.
four. Chromium is used in stainless steel and chrome plating.
5. Mo is used in X-rays tubes. Pt is used in resistance thermometers.
6. Cd is used for making joints in jewellery.
7. Ce is used as a scavenger of oxygen and sulphur in many metals-
8. Alkaline solution of GtwoHgI4 is called Nessler'due south reagent and is used to exam the presence of ammonium ion (NH+ 4).
1. Potassium Dichromate (K2 Crii O7)
Ore Ferrochrome or chromite (FeO· Cr2O3) or (FeCr2O4)
Preparation
Sodium dichromate is more soluble than potassium dichromate.
Chromates and dichromates are interconvertible in aqueous solution depending upon pH of the solutions.
Properties Sodium and potassium dichromates are potent oxidising agents, thus, acidified K2Cr27 volition oxidise iodides to iodine, sulphides to sulphur, tin (ll) to tin (IV) and fe (ll) salts to iron (III).
Uses
1. K2Cr27 is used as oxidising agent in volumetric analysis.
2. Information technology is used in mordant dyes, leather manufacture, photography (for hardening of film).
3. It is used in chromyl chloride test.
4. It is used in cleaning glassware.
2. Potassium Permanganate (KMnO 4)
Ore Pyrolusite (MnO2)
Training
Commercial grooming
Properties KMnO4 acts equally stiff oxidising agent.
1. In the presence of dilute H2SOfour, KMnO4 is reduced to manganous table salt.
Acidic KMnOfour solution oxidises oxalates to CO2, fe(II) to iron (lll), nitrites to nitrates and iodides to iodine. The half-reactions of reductants are
To acidify KMnO4, but H2SO4 is used and not HCI or HNO3 because HCI reacts with KMnO4 and produce Clii while HNO3, itself acts every bit oxidising agent.
2. In alkaline medium, KMnOfour is reduced to insoluble MnOtwo.
Alkaline or neutral KMnOfour solution oxidises I– to IO– 3, SiiO2- three to Then2- four, Mnii+ to MnO2, etc.
Aqueous KMnO4, reacts with NH$ to liberate Nii gas.
2KMnO4 + 2NH3 → 2KOH + 2MnO2 + N2 + 2H2O
Uses
KMnO4 is used
(i) in laboratory training of CI2.
(two) as an oxidising agent and disinfectant.
(iii) in making Baeyer's reagent.
Structures
3. Copper Sulphate (CUSOfour ·5HtwoO)
It is also known as bluish vitriol.
Method of preparation Information technology is obtained by the action of dil HiiAnd so4 on copper scrap in the presence of air.
Properties
1. On heating it turns white due to loss of h2o of crystallisation.
At 1000 Yard, CuSO4 decomposes into CuO and So3
2. It gives bluish solution with NH4OH and white ppt of Cu2Itwo with KI.
Uses It 1S used in electroplating, every bit mordant in dyeing, in making bordeaux mixture [(Ca(OH) 2 + CuSO4)], etc.
4. Silver Nitrate (AgNOthree)
It is besides called Lunar caustic.
Method of preparation Information technology is prepared by heating silver with dilute nitric acid
Backdrop
1. It is colourless, crystalline compound which blackens when comes in contact of organic substances (pare, cloth, etc.)
2. With potassium dichromate, information technology gives cherry-red ppt of Ag2CrO4.
three. On strong heating, it decomposes to metal silver.
4. Ammoniacal solution of silver nitrate is known every bit Tollen's reagent.
Uses It is used as laboratory reagent, in silvering of mirror, in the preparation of inks and pilus dyes, etc.
Inner-Transition Elements
The elements in which the filling of atomic orbitals past electrons accept identify in {-subshells, 2 levels inside the outer subshell, are known as inner-transition elements. They are also known as f-block elements
Classification of f-block Elements
They have been classified into two series.
(a) 4f-series (first inner-transition series) The concluding electron enters in 4f-orbital. The elements belonging to this series are also known equally lanthanoids.
(b) 5f-serial (second inner-transition series) The last electron enters in 5f-orbital. The elements belonging to this series are as well known as actinides.
Lanthanides
The xv elements from lanthanum (at. no. 57) to lutetium (at. no. 71) are known as lanthanides or rare earths. Their properties are as follows :
1. Electronic configuration
The general electronic configuration of these elements is [Xe]4f0 – 14 5d0-1 6stwo. The lanthanum, electronic configuration [Xe]4f0 5d1 6s2 and lutetium, electronic configuration [Xe]4f14 5d1 6s2, accept no partially filled 4f-orbital in their ground country, are considered as lanthanides due to their properties shut to these elements.
2. Oxidation country
The virtually common and about stable oxidation state of lanthanides is +iii but some elements as well exhibit +ii and +4 oxidation states in which they get out behind stable ions, east.thousand.,
An aqueous solution of Ce4+ is a expert oxidising agent. The Eu2+ and Yb2+ tin can exist in aqueous solution and are good reducing agents. Merely there are exceptions as well e.k.,
iii. Magnetic properties
Magnetic backdrop have spin and orbit contributions. Hence, magnetic moments are given by the formula
μ = √4S(S + i)+ L (L + 1)
Where, L = orbital quantum number, Southward = spin breakthrough number
All lanthanide ions with the exception of La3+, Lu3+ and Ce4+, are paramagnetic in nature.
four. Lanthanoid contraction
Steady subtract in the atomic and ionic (Ln3+) radii as the atomic Dumber of the lanthanide elements increases is called lanthanide contraction. This is because the additional electron goes to 4f-subshell and 4f-orbitals being large and lengthened, have poor shielding event. The effective nuclear accuse increases which causes the contraction in the size of electron charge cloud. This contraction in size is quite regular and is known every bit lanthanoid contraction.
The f- f transitions are possible due to absorption of light from the visible region.
Consequences of lanthanoid contraction
(i) Covalent grapheme of cations increase.
(ii) The electronegativity of trivalent ions increases slightly.
(iii) At that place is decrease in bones strength of oxides and hydroxides from La to Lu.
(iv) In that location is pocket-sized increase in standard electrode potential values.
(five) Sizes of Zr and Hf; Nb and Ta are like, so they are called chemical twins.
five. Color
The species containing unpaired electrons are coloured and so on in the case of lanthanide ions.
half-dozen. Melting and boiling pOints
Lanthanides accept high melting and boiling points but in that location is no regular trend.
7. Density
Lanthanides have densities varying . from 6.67 to ix.7 k cm-3, merely there IS no regular tendency for these values.
viii. Electronegativity
For lanthanides the electronegativity values are almost same as that of $-block elements. Lanthanides form ionic compounds.
ix. Ionisation energies
The ionisation energy values of lanthanoids are not very high due to their large size and comparable with those of alkali metal world metals.
x. Circuitous compound
Due to their large ionic SIze, they have little tendency to form complexes.
11. Reactivity
Due to their depression values of ionisation energies, the lanthanides are very reactive.
12. Alloys
They form alloy peculiarly with fe east.g., misch metal rare earths 94 _ 95%, atomic number 26 ~ five% and S, C, Ca and AI in traces. Mg mixed with 3% misch metal is used for making jet engine parts.
Actinides
The fifteen elements from actinium (at. no. 89) to lawrencium (at. no. 103) are known as actinides and constitute the 5f series. From neptunium to onwards the elements are man-made (artificially prepared) and likewise known every bit transuranic elements.
1. Electronic configuration
The final electron in such elements enters in the 5f atomic orbital.
Their general electronic configuration is
[Rn]5 f0 – fourteen 6d0 – one 7s2
At that place is not much difference between the energies of 5f and 6d, so it is hard to predict whether the electron has entered in 5f or 6d.
ii. Oxidation state
The common oxidation state is +three but other oxidation states are too exhibited by actinides upto the maximum being +7.
3. Magnetic properties
The magnetic moments of actinide ions are smaller than theoretical values. Information technology is hard to interpret due to large spin orbit coupling.
4. Actinide contraction
It is similar to lanthanide contraction due to poor shielding or 5f – electrons
5. Melting and humid points
They have loftier values for melting and boiling points just there is no regular trend.
6. Density
The value of density vary from 7.0 gcm-3 to xx gcm-iii. Again in that location is no regular trend in density.
7. Reducing character
They are strong reducing agents equally they accept high E° values approximately 2.0 V.
8. Reactivity
Actinide are very reactive in nature and combine with oxygen and halogens like lanthanoids.
9. Coloured ions
Actinide ions are coloured due to the presence of unpaired electrons and f-f transitions.
10. Complex formation
They accept college tendency to class complex compounds.
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