D Block Elements

Series of elements formed by progressive filling of 3d, 4d, 5d shells of electrons

Aka transition elements

D block elements are known as TM's because their properties are transitional between those of s block and p block elements.

New definition by IUPAC;

Transition metals are metals having incomplete d subshell (either in ionic form or neutral atom)

Zinc, Cadmium, mercury of G12

Because their d subshells are completely filled in both their ground state as well as common oxidation states.

d¹⁰ configuration

Transition metals are metals having incomplete d subshell either in ground state or excited state(most common OS)

Special character: d orbitals of Transition metals protrude to periphery of atom MORE than other orbitals. => Thus, more influenced by surroundings AND affect surrounding atoms or molecules.

Propertie

(typical metallic properties)

• metallic lustre

•malleability and ductility

•thermal and electric conductivity

•low volatility

•hard and high tensile strength

•high MP and BP

High Melting points of these metals are attributed to the involvement of greater number of electrons from (n-1)d subshell in addition to na electrons in interatomic metallic bonding. (Because we know that energy diff between (n-1)d subshell and ns shell is very low due to low shielding effect of d orbitals)

In any row, MP's of these metals rise to a maximum at d⁵ except for anomalous values of Mn and Tc.

And fall regularly as atomic number increases.

TM's have high enthalpies of atomisation

Variation resembles that of melting point.

The maxima at about the middle of each series indicates that enthalpy of atomisation is directly related to the number of unpaired electrons.

Unpaired electrons in d subshell are favourable for strong interatomic interaction.

Greater the number of unpaired electrons, stronger is the resultant bonding.

Metals of 2nd and 3rd series have greater ∆aH = explains why there is much more frequent metal-metal bonding in compounds of heavy TM's

Because they have greater enthalpies of atomisation

• progressive decrease in radius with increasing atomic number.

Reason: each time the nuclear charge increases by unity, a new electron enters a d orbital

{ Also, shielding effect of d electron is NOT that effective, thus effective nuclear charge increases along the series and ionic radius decreases ATP.}

•Variation within a series is quite small

• comparison of atomic size of 1 series compared to those of corresponding elements in other series:

There's an increase in atomic size from corresponding elements of 3d series to those of 4d series .

BUT----corresponding radii of elements of 4d and 5d series are virtually the same.

Before the 5d series of elements begin, the filling of 4f orbitals must take place (which happens in the lanthanide series) which results in greater-than-expected decrease in ionic radii of elements in lanthanide series(due to poor sheilding effect of 4f electrons). (In one word, lantanoid contraction)

It's the greater-than-expected decrease in ionic/atomic radii of elements in lanthanide series due to low shielding effect of 4f electron.

This can explain why the radii of elements of 4d and those of corresponding elements of 5d are virtually the same.(before 5d series begins, filling of 4f subshell must take place, which results in smaller than otherwise expected ionic radii for 5d series)

Obviously, IE¹ increases (only slightly) along the series with increase in atomic number because of increase in Z effective. (Slightly because atomic radii decrease less rapidly due to shielding of d orbitals towards 4s electrons)

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There are irregularities in the trend though. That can be mainly attributed to loss of exchange energy.Loss of exchange energy is responsible for greater stability of ions/ atoms having completely filled subshell (d¹⁰) followed by half filled subshells (e.g. elements/ions having d⁵ configuration).

Loss of exchange energy is responsible for greater stability of ions/ atoms having completely filled subshell (d¹⁰) followed by half filled subshells (e.g. elements/ions having d⁵ configuration).

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General trend of increasing values of IE² as Zeff increases

General trend because it isn't complicated by shielding of s electrons by d electrons anymore (since M² and M³ ions have d* configuration)

•Trend of steady increase in IE² is broken for formation of Mn²

• Trend of steady increase in IE³ breaks for formation of Fe ³

S¹: write the electronic configurations of Mn¹+ and Cr¹+.

S²: state which one has a stable configuration and claim 'loss of exchange energy' and 'more stability' and state 'which one is harder to ionise' as the reason for that.

Same reasons. STOP BEING LAZY AND TRY IT OUT!

•Second ionisation enthalpies have unusually high values for Cr and Cu (where M+ ions have d⁵ and d¹⁰ configurations. Thus, it's harder to ionise them)

•IE² for Zinc is correspondingly low because ionisation of Zn+ results in stable d¹⁰ configuration.

• are Quite high

• high values for third ionisation enthalpies of Co, Ni, and Zn . (Possible reasons as for why it's difficult to obtain OS greater than 2 for these elements)

(electrode reduction potential; tendency to get reduced= -tendency to get oxidised)

• General trend along the series: becomes less negative along the series.

Reason; general increase in sum of ionisation enthalpies (IE¹+IE²)

• IRREGULARITIES: MORE negative values of Mn, Ni, Zn (munizan)

Note: more negative value of electrode potential= more OP(i.e. tendency to get oxidised)

It WANTS to get oxidised to M² - indicating that its M² form is more stable/has stable electronic configuration. - possible reasons for Mn and Zn

Whereas for Ni- it has the highest negative hydration enthalpy.

• shoulda generally increased/become less negative

But there are many irregularities

•Values comparatively more negative;

Sc and Fe ; reflects the stability of their M³ ions. Sc³ has NG configuration whereas Fe³ has d⁵ configuration.

•Values comparatively high/less negative/more positive;

Zn and Mn ; because of their stable configuration in M² ions. Highest value of Zn.

Halides

•highest oxidation numbers are achieved in TiX⁴, VF⁵ and CrF⁶

• +7 in Mn is NOT represented by simple halides. Instead it's represented by MnO³F.

• Beyond Mn, trihalides are NOT found other than FeX³, and CoF³

• V⁵ is represented only by VF⁵; other V⁵ halides undergo hydrolysis to form VOX³

•instability of flourides in low Oxidation states (e.g.VX² and CuX)

Iodides.

. Reaction of Cu² with iodide gives Cu²I² [Cu(1) iodide]

Cu(1) compounds are unstable in aq solution and undergo disproportionation to form Cu² and Cu⁰

Because Cu² has much more negative hydration enthalpy which compensates for IE² of Cu.

Reaction:

Cu(1) compounds are unstable and undergo disproportionation in aqueous solution to yield Cu² and Cu⁰

• high lattice energy in case of CoF³

• higher bond enthalpy in case of VF⁵ and CrF⁶

Whenever a substance is placed in MF, 2 types of behaviours are observed: para and diamagnetism

Most TM ions are paramagnetic: which arises due to presence of unpaired electrons( which have magnetic moment associated with its spin angular momentum and orbital angular momentum ).

• But for compounds of TM of 1st series, contribution of orbital angular momentum is effectively quenched .

This, magnetic moment is determined by number of unpaired electrons ; and calculated by spin-only formula.

u= √n(n+2) BM (Bohr's magneton)

Complex compounds: compounds in which metal ions bind a number of ligands(neutral or charged molecules/ions) to form complex species with special characteristics.

•give a couple of God damned examples, will ya! [Co(NH³)⁶]³+

• TM's form a large number of complex compounds. Reasons

•availibility of d orbitals for bond-formation

•high ionic charges.

• comparatively smaller sizes of metal ions. (In my intuition enables them to bind a number of ligands)

{ In short, availability of d orbitals for bond-formation AND high charge to radius ratio value}

Ln³+

Series of elements formed by filling of f orbitals. (The last electron enters the f orbital in these elements)

It consists of 2 series:

lanthanoids(14 elements following lanthanum starts: Cerium and ends with Lutetium)

Actinoids (14 elements following actinium)

Members esemble one another more closely than do the member of any other transition series.

They have only one stable oxidation state (Ln³) .

Characteristic feature: lanthanoid contraction;

• electronic configuration

• atomic sizes

• oxidation states

• General characteristics -chemical behaviour

• describe yourself like a narcissist would- soft, white, silvery,

•tarnishes rapidly in this crooked world(i.e. air)

• Hardness : very hard, especially Samarium(hard-hearted)

• High MP's: 1000-1200K but Sm has 1623K

•typical metallic lustre

•good conductors(heat and electricity)

• Colour: most ions are coloured.(attributed to presence of f electrons)

• Magnetic properties: most are paramagnetic except f¹⁴ and f⁰ configurations.

Many Ln³ ions are coloured except La³ and Lu³.

Absorption bands are narrow.

(Reason: excitation takes place within f level)

All Ln ions are paramagnetic except

•f⁰- La³Ce⁴

•f¹⁴- Lu³Yb²

IE¹- app. 600kJ/mol

IE²- 1200

IE³- discussion indicates the loss of EE imparts stability to empty, half, completely filled f subshell.

Abnormally low IE³- (La G ge d Lu tetium) La, Gd, Lu (lagged Lutetium)

[comparable with those of Ca]

•alloy steel production- mischmetall ;

M's

consist of Ln(95%), Fe and other M's and NM's- which in turn is used in Mg-based alloys to produce bullets, shells etc.

• Mixed oxides of Ln; employed as catalysts in petroleum cracking.

• individual Ln oxides - used as phosphors in tV screens etc