Transition elements or d and f block elements

Transition elements 

 d and f block elements 

Definition: The elements which have partially filled d or f orbitals either in atomic state are in anyone of possible their Oxidation state are called transition elements

Question: Why are they called transition elements?

Answer. They are called transition elements because they show properties which are in between s block and p block elements.

Series of d-Block Elements

There are four series of d block elements: 

First outer transition elements: These elements are from scandium (₂₁Sc) to zinc (₃₀Zn). It is also called 3d series.

Second outer transition elements: These elements are from yttrium (₃₉Y )to cadmium (₄₈Cd). It is also called 4d series.

Third outer transition series: This series ranges from lanthanum to ₈₀Hg  it is also 5d series.

 Fourth outer transition  series: elements this series Rain from antonym ₈₉AC  onward it is also called 6-d series.

General outermost electronic configuration of transition elements( n - 1)d^1-10, ns^1-2

 f- block elements:

These are two series of elements.

First inner transition series: This series is from Cadmium (₅₈Cd)  to lanthanum  (₇₁La). It is also called Lanthanide or 4 f series.

Second inner transition series: It ranges from Thorium ₉₂Th  to lawrencium ₁₀₃Lr 103. It is also called actinide or 5 f series.

Question: Why zinc (IIB) group elements are called called Transition Elements?

Zing group contain zinc cadmium and mercury (Zn, Cd and Hg).  This group is not regarded as transition elements because they have completely filled d-orbital. These elements have  been included in transition elements because they form complexes with ammonia, halide ions, amine etc., and their chemical behavior is similar to transition elements.

Question why coinage metals are are transition elements?

Coinage metals are copper (Cu) silver (Ag) and gold (Au). These are transition elements as Cu²⁺ has 3d⁹ configuration ,  Ag²⁺ has 4d⁹ configuration  and Au³⁺ has 5d⁸ configuration . Therefore, they are called college metals.

Question: Differentiate between typical and non typical  transition elements.

Typical transition elements

Transition elements other than IIB and III B are called typical transition elements.

Non typical Transition Element

IIB and IIIB elements are called non typical transition elements. The electronic configuration of non typical transition elements is given as follows.

IIB

Zn ........ 4s²3d¹⁰

Cd......... 5s²4d¹⁰

Hg.......... 6s²5d¹⁰

IIIB

Sc .....4s²3d¹

Y.....5s²4d¹

La.....6s²5d¹

Since  IIB transition elements do not have partially field d orbital in ionic atomic state, so they don't show properties a like typical transition elements. The III B transition elements do not show properties of typical transition elements as they have tri-positive which do not have any electron in  d- orbital. For these reasons,  IIB and IIIB are called non typical transaction elements.

 General Characteristics of transition elements

i. They are all metallic in nature.

ii. Some of transition elements play an important role in industry. These metals are Titanium (Ti), chromium (Cr), iron (Fe), Nickel (Ni),  copper (Cu), molybdenum (Mo),  tungsten (W),  Tin (Sn),  nibidium (Nb),  thallium (Th), etc.

iii. They are also hard and strong matals with high melting points and boiling point.

iv. They are good conductor of electricity.

v. They form alloy with other metals and other elements of the periodic table.

vi. With few exceptions, they show variable oxidation states. 

vii. Transition elements and their compounds act  as a catalyst during reactions. 

viii. They form coordination complexes .

Valence electronic configuration of 3d transition elements

₂₁Sc.........3d¹ 4s²

₂₂Ti.........3d² 4s²

 ₂₃V.........3d³ 4s²

₂₄Cr........3d⁵ 4s¹

 ₂₅Mn.........3d⁵ 4s²

₂₆Mn......... 3d⁶ 4s²

₂₇Co........3d⁷ 4s²

₂₈Ni.........3d⁸ 4s²

.₂₉Cu........3d¹⁰ 4s1

₃₀Zn.........3d¹⁰ 4s²

Question: Why there is a regularity in electronic configuration of chromium and copper?

Answer

The exactly half field and completely filled orbitals of transition elements posses extra stability. Chromium has half d orbital and copper has completely filled  d orbital, so therefore these two elements show in regularity in electronic configuration.

Binding energy

Amount of energy required to break the metallic bond is called binding energy of transition elements transition elements have very high burning energy and due to hi burning Inderjeet is matters are hard tough and high density malleable ductile they also have very high melting points and boiling point then S block elements.

Trends in binding energy in d-block elements

As we move from left to right in any d-block series the number of unpaired electrons increases up to VB  group (Mn) and VIB group (Cr), So binding energy also increases. After this pairing of electron starts,  the unpaired electrons decrease and become zero at IIB,  so binding energy also decreases.

Question why transistor elements you very block season state?

Reason is there is that transition elements have the (n-1)d electron in addition to ns electron for purpose of bonding.  These elements have several (n -1)d and ns electrons. The energy of (n-1)d and ns orbitals are very close to each other. Therefore does n - 1d electrons are easily lost ns electron. 

For example among 3d series manganese (Mn) has maximum oxidation state of +7. The oxidation state of other elements have in shown as follows.

Question: Why transition and elements act as a catalyst?

Answer. Most of the transition elements and their compound act as catalyst  due to following reasons.

i. Transition elements show variable oxygen states. In this way they form intermediate product.

ii. They also form industrial compound which can absorb reacting species.

iii. They can form an unstable intermediate compound which readily decompose to give product.

For example,

a. A mixture of ZnO  and Cr2O3 is used for manufacturing of methyl alcohol.

b. Nickel platinum and Platinum are catalyst for the hydrogenation of vegetable oil and saturation of alkene and alkyne to give alkane

c. Mn2O3 can be used as catalyst for decomposition of H2O2

d. TiCl2 is used for manufacturing of plastic.

e. V2O5 is used to oxides SO2 into SO3 in manufacturing of sulphuric acid.

f. Fe is used as a catalyst for synthesis of ammonia in Haber Process.

Magnetic behavior of Transition elements

Many transition elements and their compounds are paramagnetic ( a substance which is attracted by magnetic field is called paramagnetic). This paramagnetism is due to unpaired electrons present in metal and their compounds. 

Some transition elements are  ferromagnetic ( a substance which can be magnetize is called paramagnetic). For example, Fe, Ni and Co are ferromagnetic.

Some transition elements are diamagnetic (a substance which are slightly repelled by magnetic field are called diamagnetic). They are diamagnetic due to paired electron.

The relationship between magnetic moment and unpaired electron is given as follow

N = number of unpaire electrons the magnetic moment is measured in Bohr magneton BM

Alloy formation

Alloy is a homogenous mixture of two or more metals. Transition elements form alloy with other elements because translation elements have almost similar atomic size. Therefore atoms of one metal can easily take  up the position in crystal lactic of other.  They form substituted alloy .

For example, alloy steel are  material in which iron metal atom is substituted with Mn  and Ni

Properties of alloy

i. Alloy  are comparatively cheap.

ii. They are strong and flexible but hard alloy can also be be prepared.

iii. They have long life because they do not crude.

iv. They are durable.

v. They have high melting points. 

vi. They are better conductor but non conductor can also be prepared.

Also read: Coordination compounds, nomenclature, geometries and colors