Coordination compound is made up of a central metal atom or ion that is surrounded by a number of oppositely charged ions or neutral molecules. All the ions or molecules in coordination compounds are connected with coordinate bonds to the central metal atom. When coordination compounds are dissolved into water, they do not dissociate into simple ions which means in water it does not lose its identity. A coordination compound is also called a complex compound. Coordination compound is very important in our day to day life. It is important to recognize that chlorophyll (Mg – complex) in plants, hemoglobin (Fe- complex) in human blood and Vitamin B12 (Co -complex) are also complex compounds.  

Coordination Compounds-Coordination Entity, Central atom/ion, Ligands, Coordination number, Coordination sphere, Coordination polyhedron, Oxidation number, Homoleptic & heteroleptic complexes, FAQs

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What is Coordination Compound ?

Coordination compound is made up of a central metal atom or ion that is surrounded by a number of oppositely charged ions or neutral molecules. All the ions or molecules in coordination compounds are connected with coordinate bonds to the central metal atom. When coordination compounds are dissolved into water, they do not dissociate into simple ions which means in water it does not lose its identity. A coordination compound is also called a complex compound. Coordination compound is very important in our day to day life. It is important to recognize that chlorophyll (Mg – complex) in plants, hemoglobin (Fe- complex) in human blood and Vitamin B12 (Co -complex) are also complex compounds.  

Coordination compound is made up of a central metal atom or ion that is surrounded by a number of oppositely charged ions or neutral molecules. All the ions or molecules in coordination compounds are connected with coordinate bonds to the central metal atom. When coordination compounds are dissolved into water, they do not dissociate into simple ions which means in water it does not lose its identity. A coordination compound is also called a complex compound. Coordination compound is very important in our day to day life. It is important to recognize that chlorophyll (Mg – complex) in plants, hemoglobin (Fe- complex) in human blood and Vitamin B12 (Co -complex) are also complex compounds.  

Coordination Entity

A coordination entity is made up of a central metal atom or ion that is bonded to a set number of ions or molecules. Here [CoCl3 (NH3)3] is a coordination entity that has three chloride ions and three ammonia molecules that are connected to the cobalt ion.

Some important examples are:

  • [Ni(CO)4],
  • [PtCl2 (NH3)2],
  • [Fe(CN)6]4–, and
  • [Co(NH3)6]3+

Central atom/ion

The central atom is surrounded and coordinately bonded to one or more neutral molecules or ions in a specific geometrical arrangement and are connected with a coordinate bond. The central atoms/ions in the coordination entities [NiCl2 (H2O)4], [CoCl(NH3)5]2+, and [Fe(CN)6]3– are Ni2+, Co3+, and Fe3+, respectively.

Some important examples are:

  • K4[Fe(CN)6] – central atom/ion is : Fe+2
  • [Cu(NH3)4]SO4 – central atom/ion is : Cu+2

Ligands

Ligands are simple ions or molecules which has a tendency to donate an electron and can form a coordinate bond with the central atom /ion. Ligands can be simple ions like Cl– and Br–,  small molecules like H2O or NH3, larger molecules like H2NCH2CH2NH2 or N(CH2CH2NH2)3.

When a ligand is bound to a metal ion through a single donor atom then the ligand is said to be unidentate. Cl– , H2O or NH3 are unidentate ligands. When a ligand is connected through two donor atoms, the ligand is said to be bidentate. The H2NCH2CH2NH2 (ethane-1,2-diamine) or C2O42– (oxalate) are bidentate ligands. When there are multiple donor atoms in a single ligand, such as N(CH2CH2NH2)3, the ligand is said to be polydentate. Ethylenediaminetetraacetate ion (EDTA4–) is a hexadentate ligand it is very important. It can connect through two nitrogen and four oxygen atoms to a central metal ion. 

Ambidentate ligand is a ligand that has two different donor atoms and can be either of the two ligands in the complex. The NO2– and SCN– ions are two examples of such ligands. NO2– ion can coordinate to a central metal atom/ion via either nitrogen or oxygen. Similarly, the SCN– ion can coordinate via the Sulphur or nitrogen atom.

Coordination compound is made up of a central metal atom or ion that is surrounded by a number of oppositely charged ions or neutral molecules. All the ions or molecules in coordination compounds are connected with coordinate bonds to the central metal atom. When coordination compounds are dissolved into water, they do not dissociate into simple ions which means in water it does not lose its identity. A coordination compound is also called a complex compound. Coordination compound is very important in our day to day life. It is important to recognize that chlorophyll (Mg – complex) in plants, hemoglobin (Fe- complex) in human blood and Vitamin B12 (Co -complex) are also complex compounds.  

Some important examples are:

  • Unidentate ligands:
  • Bidentate ligands:

Coordination number

A metal ion’s coordination number (CN) in a complex is defined as the number of ligand donor atoms to which the metal is directly bonded. For example, the coordination numbers of Pt and Ni in the complex ions [PtCl6]2– and [Ni(NH3)4]2+ are 6 and 4, respectively. Similarly, the coordination number of both Fe and Co in the complex ions [Fe(C2O4)3]3– and [Co(en)3]3+ is 6 because C2O42– and en (ethane-1,2-diamine) are bidentate ligands.

It should be noted that the coordination number of the central atom/ion is determined solely by the number of sigma bonds formed by the ligand with the central atom/ion. This calculation excludes pi bonds formed between the ligand and the central atom/ion..

Some important examples are:

  • K4[Fe(CN)6] – coordination number = 6
  • [Ni(CO)4]   – coordination number = 4

Coordination sphere

The coordination sphere is made up of the central atom/ion and the ligands that are attached to it. The ionisable groups are denoted by a bracket and are referred to as counter ions. 

Some important examples are:

In the complex K4[Fe(CN)6]: the coordination sphere is [Fe(CN)6]4– and the counterion is K+.

Coordination polyhedron

A coordination polyhedron is defined by the spatial arrangement of the ligand atoms that are directly attached to the central atom/ion. Octahedral, square planar, and tetrahedral polyhedra are the most common coordination polyhedra.

Some important examples are:

  • [Co(NH3)6]3+ is octahedral,
  • [Ni(CO)4] is tetrahedral, and
  • [PtCl4]2– is square planar.

Oxidation number of central atom

The oxidation number of the central atom in a complex is defined as the charge it would carry if all of the ligands and electron pairs shared with the central atom were removed. The oxidation number is represented by a Roman numeral in parenthesis after the coordination entity’s name.

Some important examples are:

  • The oxidation number of copper in [Cu(CN)4]3– is +1 and is written as Cu (I).
  • The oxidation number of ferrous in K4[Fe(CN)6] is +2 and it is written as Fe(II).

Homoleptic and heteroleptic complexes

Homoleptic complexes are those in which a metal is bound to only one type of donor group, such as [Co(NH3)6] 3+. Heteroleptic complexes are those in which a metal is bound to more than one type of donor group, such as [Co(NH3)4Cl2] +.

Some important examples are:

  • Homoleptic complexes:
  • Heteroleptic complexes:
    • [Co(NH3 )4 (H2O)Cl]Cl2 
    • [Pt(NH3 )2Cl(NO2 )]

Sample Questions(FAQs)

Question 1: Write the central atom/ion in the following compound-

  1. K2[Zn(OH)4]
  2. [Co(NH3 )4(H2O)Cl]Cl2 
  3. K3 [Al(C2O4 )3 ]
  4. [CoCl2 (en)2 ]+
  5. [Ni(CO)4 ]

Answer:

  1. Central atom of K2[Zn(OH)4] is                      –          Zn
  2. Central atom of [Co(NH3 )4 (H2O)Cl]Cl2 is     –          Co
  3. Central atom of K3 [Al(C2O4 )3 ] is                 –          Al
  4. Central atom of [Pt(NH3 )2Cl(NO2 )]+ is        –           Pt
  5. Central atom of [Ni(CO)4 ] is                         –           Ni

Question 2:  Write the coordination number of the following coordinate compounds-

  1. K4[Fe(CN)6] 
  2. [Ni(CO)4]
  3. K3[Al(C2O4 )3]

Answer:

  1. K4[Fe(CN)6]            –   coordination number =  6
  2. [Ni(CO)4 ]               –   coordination number = 4
  3. K3 [Al(C2O4 )3 ]    –   coordination number =  6

Question 3: What are ambidentate ligands give examples?

Answer:

A molecule or an ion that has two donor atoms but only one of them forms a coordinate bond with the central metal atom is referred to as a ambidentate ligands.

Some important examples are:

  • CN–
  • NC:–
  • NO2-
  • ONO:–

Question 4: Write all the ligands present in the following coordination compounds-

  1. [Pt(NH3)6]4+
  2. [Co(NH3)2Cl2(en)]+
  3. [CO(NH3)5NO2]2+
  4. [Cu(Br)4]2-

Answer:

  1. Ligands in [Pt(NH3)6]4+ are : NH3
  2. Ligands in [Co(NH3)2Cl2(en)]+ are: NH3,  Cl–,  en
  3. Ligands in [CO(NH3)5NO2]2+ are: NH3,  NO2-
  4. Ligands in [Cu(Br)4]2- are: Br–

Question 5: Find the oxidation number of the metals in the following complex compounds-

  1. Co(H2O)(CN)(en)2]2+ 
  2. [CoBr2(en)2]+ 
  3. [PtCl4]2- 
  4. K3[Fe(CN)6] 
  5. [Cr(NH3)3CI3]

Answer:

1. Co(H2O)(CN)(en)2]2+ 

         Oxidation number:   x + 0 + (-1) + 0 = +2

                                         x = +3

2. [CoBr2(en)2]+

         Oxidation number:    x + 2*(-1) + 0 = +1

                                          x = +3

3. [PtCl4]2-

         Oxidation number:  x + (-4) = -2

                                        x = +2

4. K3[Fe(CN)6]

         Oxidation number:   3*(+1) + x + 6*(-1) = 0

                                         x = +3

5. [Cr(NH3)3CI3]

         Oxidation number:   x + 0 + 3*(-1) = 0

                                         x = +3

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

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CBSE Class 12 Chemistry Syllabus Download PDF

Below is the CBSE Class 12 Syllabus along with the marking scheme and time duration of the Chemistry exam.

S.NoTitleNo. of PeriodsMarks
1Solutions107
2Electrochemistry129
3Chemical Kinetics107
4d -and f -Block Elements127
5Coordination Compounds127
6Haloalkanes and Haloarenes106
7Alcohols, Phenols and Ethers106
8Aldehydes, Ketones and Carboxylic Acids108
9Amines106
10Biomolecules127
Total70

CBSE Class 12 Chemistry Practical Syllabus along with Marking Scheme

The following is a breakdown of the marks for practical, project work, class records, and viva. The total number of marks for all parts is 15. The marks for both terms are provided in the table below.

Evaluation Scheme for ExaminationMarks
Volumetric Analysis08
Salt Analysis08
Content-Based Experiment06
Project Work and Viva04
Class record and Viva04
Total30

CBSE Class 12 Chemistry Syllabus (Chapter-wise)

Unit -1: Solutions

  • Raoult's law.
  • Colligative properties - relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties, abnormal molecular mass.
  • Solutions, Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions.
  • Van't Hoff factor.

Unit -2: Electrochemistry

  • Redox reactions, EMF of a cell, standard electrode potential
  • Nernst equation and its application to chemical cells
  • Relation between Gibbs energy change and EMF of a cell
  • Kohlrausch's Law
  • Electrolysis and law of electrolysis (elementary idea)
  • Dry cell-electrolytic cells and Galvanic cells
  • Conductance in electrolytic solutions, specific and molar conductivity, variations of conductivity with concentration.
  • Lead accumulator
  • Fuel cells

Unit -3: Chemical Kinetics

  • Rate of a reaction (Average and instantaneous)
  • Rate law and specific rate constant
  • Integrated rate equations and half-life (only for zerfirst-order order reactions)
  • Concept of collision theory (elementary idea, no mathematical treatment)
  • Factors affecting rate of reaction: concentration, temperature, catalyst;
  • Order and molecularity of a reaction
  • Activation energy
  • Arrhenius equation

Unit -4: d and f Block Elements  

  • Lanthanoids- Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction and its consequences.
  • Actinoids- Electronic configuration, oxidation states and comparison with lanthanoids.
  • General introduction, electronic configuration, occurrence and characteristics of transition metals, general trends in properties of the first-row transition metals – metallic character, ionization enthalpy, oxidation states, ionic radii, color, catalytic property, magnetic properties, interstitial compounds, alloy formation, preparation and properties of K2Cr2O7 and KMnO4.

Unit -5: Coordination Compounds  

  • Coordination compounds - Introduction, ligands, coordination number, color, magnetic properties and shapes
  • The importance of coordination compounds (in qualitative analysis, extraction of metals and biological system).
  • IUPAC nomenclature of mononuclear coordination compounds.
  • Bonding
  • Werner's theory, VBT, and CFT; structure and stereoisomerism

Unit -6: Haloalkanes and Haloarenes  

  • Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only). Uses and environmental effects of - dichloromethane, trichloro methane, tetrachloromethane, iodoform, freons, DDT.
  • Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions.

Unit -7: Alcohols, Phenols and Ethers   

  • Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophilic substitution reactions, uses of phenols.
  • Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses.
  • Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration, and uses with special reference to methanol and ethanol.

Unit -8: Aldehydes, Ketones and Carboxylic Acids   

  • Carboxylic Acids: Nomenclature, acidic nature, methods of preparation, physical and chemical properties; uses.
  • Aldehydes and Ketones: Nomenclature, nature of carbonyl group, methods of preparation, physical and chemical properties, mechanism of nucleophilic addition, the reactivity of alpha hydrogen in aldehydes, uses.

Unit -9: Amines    

  • Diazonium salts: Preparation, chemical reactions and importance in synthetic organic chemistry.
  • Amines: Nomenclature, classification, structure, methods of preparation, physical and chemical properties, uses, and identification of primary, secondary and tertiary amines.

Unit -10: Biomolecules     

  • Proteins -Elementary idea of - amino acids, peptide bond, polypeptides, proteins, structure of proteins - primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins; enzymes. Hormones - Elementary idea excluding structure.
  • Vitamins - Classification and functions.
  • Carbohydrates - Classification (aldoses and ketoses), monosaccharides (glucose and fructose), D-L configuration oligosaccharides (sucrose, lactose, maltose), polysaccharides (starch, cellulose, glycogen); Importance of carbohydrates.
  • Nucleic Acids: DNA and RNA.

The syllabus is divided into three parts: Part A, Part B, and Part C. Part A consist of Basic Concepts of Chemistry, which covers topics such as atomic structure, chemical bonding, states of matter, and thermochemistry. Part B consists of Topics in Physical Chemistry, which includes topics such as chemical kinetics, equilibrium, and electrochemistry. Part C consists of Topics in Organic Chemistry, which covers topics such as alkanes, alkenes, alkynes, and aromatic compounds.

Basic Concepts of Chemistry:

  • Atomic structure: This section covers the fundamental concepts of atomic structure, including the electronic configuration of atoms, the Bohr model of the atom, and the wave nature of matter.
  • Chemical bonding: This section covers the different types of chemical bonds, including ionic, covalent, and metallic bonds, as well as the concept of hybridization.
  • States of the matter: This section covers the three states of matter - solid, liquid, and gas - and the factors that influence their properties.
  • Thermochemistry: This section covers the principles of thermochemistry, including the laws of thermodynamics and the concept of enthalpy.

Chapters in Physical Chemistry:

  • Chemical kinetics: This section covers the study of the rate of chemical reactions and the factors that influence it, including the concentration of reactants, temperature, and the presence of catalysts.
  • Equilibrium: This section covers the principles of chemical equilibrium, including the concept of Le Chatelier's principle and the equilibrium constant.
  • Electrochemistry: This section covers the principles of electrochemistry, including the concept of half-cell reactions, galvanic cells, and electrolysis.

Chapters in Organic Chemistry:

  • Alkanes: This section covers the properties and reactions of alkanes, including their structure, isomerism, and combustion.
  • Alkenes: This section covers the properties and reactions of alkenes, including their structure, isomerism, and addition reactions.
  • Alkynes: This section covers the properties and reactions of alkynes, including their structure, isomerism, and addition reactions.
  • Aromatic compounds: This section covers the properties and reactions of aromatic compounds, including their structure, isomerism, and electrophilic substitution reactions.

In addition to the topics covered in the syllabus, the CBSE Class 12 Chemistry exam also tests students on their analytical and problem-solving skills, as well as their ability to apply the concepts learned in the classroom to real-world situations.

Students can also check out the Tips for the Class 12 Chemistry Exam. They can easily access the Class 12 study material in one place by visiting the CBSE Class 12 page at ANAND CLASSES (A School Of Competitions). Moreover, to get interactive lessons and study videos, download the ANAND CLASSES (A School Of Competitions) App.

Frequently Asked Questions on CBSE Class 12 Chemistry Syllabus

Q1

How many chapters are there in the CBSE Class 12 Chemistry as per the syllabus?

There are 10 chapters in the CBSE Class 12 Chemistry as per Syllabus. Students can learn all these chapters efficiently using the study materials provided at ANAND CLASSES (A School Of Competitions).

Q2

What is the marking scheme for CBSE Class 12 Chemistry practical exam according to the syllabus?

The marking scheme for CBSE Class 12 Chemistry practical exam, according to the syllabus, is 8 marks for volumetric analysis, 8 marks for salt analysis, 6 marks for the content-based experiment, 4 marks for the project and viva and 4 marks for class record and viva.

Q3

Which is the scoring chapter in Chemistry as per CBSE Class 12 syllabus?

The chapter Electrochemistry in Chemistry is the scoring chapter as per CBSE Class 12 syllabus.

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