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What Is Inorganic Chemistry?

Inorganic Chemistry is a branch of Chemistry that mainly deals with the synthesis and behaviour of organometallic and inorganic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. 

Many inorganic compounds are ionic compounds, consisting of cations and anions joined by ionic bonding. Important classes of inorganic compounds are oxides, carbonates, sulphates, and halides. Many inorganic compounds are characterised by high melting points. Inorganic salts typically are poor conductors in the solid state. Other important features include their high melting point and ease of crystallisation. Where, some salts (for example, NaCl) are very soluble in water, others (for example, FeS) are not.

Inorganic chemistry finds a high number of applications in various fields, such as Biology, Chemicals, Engineering, etc. It is also applied in the field of medicine and in healthcare facilities.

The most common application is the use of common salt or the compound sodium hydroxide in our daily lives. Baking soda is used in the preparation of cakes and other foodstuffs. Many inorganic compounds are utilised in ceramic industries. In the electrical field, it is applied to electric circuits as silicon in computers, etc.

Classification of Inorganic Compounds

The organic compounds that are classified under inorganic chemistry are as follows:

Acids: Acids are those compounds that dissolve in water and generate hydrogen ions or H+ Ions. Examples of acids include hydrochloric acid, citric acid, sulphuric acid, vinegar, etc. An example of the acidic reaction is shown below:

Hydrochloric acid + water → H⁺ + Cl

Bases: A base is a type of substance or a compound that produces hydroxyl ions when kept in water. The bases like potassium hydroxide, calcium hydroxide, ammonia, and sodium hydroxide produce OH- ions when dissolved in water.

Potassium Hydroxide + H2O → K⁺ + OH^–

Salts: You might be familiar with the word ‘salt’. The substances obtained as a result of the reaction between an acid and a base are called salt. The table salt of sodium hydroxide is one of the typical examples of salt.

Oxides

The compounds that consist of one oxygen atom are called oxides.

Important Topics in Inorganic Chemistry

• Periodic Table and Its Properties
• Hydrolysis
• Metallurgy & Isolation
• Hydrogen
• S-Block Elements
• P-Block Elements
• D & F-Block Elements
• Coordination Compounds
• Environmental Chemistry

Coordination Compounds

Coordination compounds found their applications long before the establishment of inorganic chemistry. A systematic investigation of structure and bonding in coordination chemistry began with the inquisitiveness of Tassaert, which was extended by distinguished chemists like Wilhelm Blomstrand, Jorgensen and Alfred Werner until the end of the nineteenth century. In the events, Werner’s coordination theory became the basis of modern coordination chemistry.

Postulates of Werner’s Theory

• The central metal atom in the coordination compound exhibits two types of valency, namely, primary and secondary linkages or valencies.
• Primary linkages are ionisable and are satisfied by the negative ions.
• Secondary linkages are non-ionisable. They are satisfied by negative ions. Also, the secondary valence is fixed for any metal and is equal to its coordination number.
• The ions bounded by the secondary linkages to the metal exhibit characteristic spatial arrangements corresponding to different coordination numbers.

Werner’s Theory Limitations

1. It fails to explain the magnetic, colour and optical properties shown by coordination compounds.
2. It failed to explain the reason why all elements don’t form coordination compounds.
3. It failed to explain the directional properties of bonds in coordination compounds.
4. This theory does not explain the stability of the complex
5. This theory could not explain the nature of complexes

Important Terms Involving Coordination Compounds

The definitions of some important terms in the chemistry of coordination compounds can be found below.

Coordination Entity

A chemical compound in which the central ion or atom (or the coordination centre) is bound to a set number of atoms, molecules, or ions is called a coordination entity.

Some examples of such coordination entities include [CoCl3(NH3)3] and [Fe(CN)6]4-.

Central Atoms and Central Ions

As discussed earlier, the atoms and ions to which a set number of atoms, molecules, or ions are bound are referred to as the central atoms and the central ions.

In coordination compounds, the central atoms or ions are typically Lewis acids and can, therefore, act as electron-pair acceptors.

Ligands

The atoms, molecules, or ions that are bound to the coordination centre or the central atom/ion are referred to as ligands.

These ligands can either be a simple ion or molecule (such as Cl– or NH3) or in the form of relatively large molecules, such as ethane-1,2-diamine (NH2-CH2-CH2-NH2).

Coordination Number

The coordination number of the central atom in the coordination compound refers to the total number of sigma bonds through which the ligands are bound to the coordination centre.

For example, in the coordination complex given by [Ni(NH3)4]2+, the coordination number of nickel is 4.

Coordination Sphere

The non-ionisable part of a complex compound consists of a central transition metal ion surrounded by neighbouring atoms or groups enclosed in a square bracket. The coordination centre, the ligands attached to the coordination centre, and the net charge of the chemical compound as a whole form the coordination sphere when written together.

This coordination sphere is usually accompanied by a counter ion (the ionisable groups that attach to charged coordination complexes).

Example: [Co(NH3)6]C/3 – coordination sphere

Coordination Polyhedron

The geometric shape formed by the attachment of the ligands to the coordination centre is called the coordination polyhedron. Examples of such spatial arrangements in coordination compounds include tetrahedral and square planar.

Oxidation Number

The oxidation number of the central atom can be calculated by finding the charge associated with it when all the electron pairs that are donated by the ligands are removed from it.

Ligands

The surrounding atoms, ions and molecules around the central transition metal ion are known as ligands. They act as Lewis bases and donate electron pairs to transition metal ions, and thus, a dative bond is formed between ligands and the transition metal ion. Hence, these compounds are coordination complexes.

Isomerism in Coordination Compounds

Two or more compounds that have the same chemical formula but a different arrangement of atoms are known as isomers. Due to this difference in the arrangement of atoms, coordination compounds pre-dominantly exhibit two types of isomerism, namely stereo-isomerism and structural isomerism.

P-Block Elements

The elements placed in Group 13 to Group 18 of the periodic table constitute the p-block. The properties of inorganic chemistry p block elements, like that of other block elements, are greatly influenced by their atomic size, ionisation enthalpy, electron gain enthalpy and electronegativity. 

The absence of d-orbitals in the second period and the presence of d- or f-orbitals in heavier elements has a significant effect on the properties of the elements, and therefore, heavier p-block elements differ from their lighter congeners.

F-Block Elements

Elements whose f orbital gets filled up by electrons are called f-block elements. These elements have electrons (1 to 14) in the f orbital, (0 to 1) in the d orbital of the penultimate energy level and in the outermost’s orbital. F-block elements are divided into two series, namely lanthanoids and actinoids. This block of elements is often referred to as inner transition metals because they provide a transition in the 6th and 7th row of the periodic table, which separates the s-block and the d-block elements.

D-Block Elements

Elements having electrons (1 to 10) present in the d-orbital of the penultimate energy level and in the outermost ‘s’ orbital (1-2) are d-block elements. Although electrons do not fill up ‘d’ orbital in the group 12 metals, their chemistry is similar in many ways to that of the preceding groups, and so they are considered d-block elements. D-block elements are the elements that can be found from the third group to the twelfth group of the modern periodic table. The valence electrons of these elements fall under the d orbital. D-block elements are also referred to as transition elements or transition metals. 

Hydrolysis

Hydrolysis is a common form of a chemical reaction where water is mostly used to break down the chemical bonds that exist between a particular substance. Usually, in hydrolysis, the water molecules get attached to two parts of a molecule. One molecule of a substance will get an H+ ion, and the other molecule will receive the OH- group. The hydrolysis reaction is mainly used to break down polymers into monomers.

There are several types of hydrolysis, and they are as follows:

Salts: This is the most common type of hydrolysis. Hydrolysis of salts generally refers to the reaction of salt with water, where it involves the interaction between cations or anions of salts and water. During hydrolysis, salt breaks down to form ions, completely or partially, depending upon the solubility factor.

Acid and Base: Acid–base-catalysed hydrolysis can be found during the hydrolysis of esters or amides. Here, the process of hydrolysis occurs when water or hydroxyl ion reacts with the carbon of the carbonyl group of the ester or amide, where new compounds are formed. The products of both hydrolyses are compounds with carboxylic acid groups.

ATP: Most biochemical reactions that occur in living organisms are in the form of ATP hydrolysis, which takes place with the help of enzymes acting as catalysts. The catalytic action of enzymes allows the hydrolysis or breaking down of proteins, lipids, oils, fats and carbohydrates.

Organometallic Chemistry

Organometallic chemistry, an interdisciplinary science in inorganic chemistry, has grown at a phenomenal pace during the last three to four decades. On the academic plane, efforts to elucidate the nature of bonds in the ever-increasing list of exciting organometallic compounds have led to a clearer understanding of the nature and variety of chemical bonds.

Organometallic compounds are primarily used as homogeneous catalysis agents in industries. The topics covered in this article offer readers new insights into the field of organometallic chemistry.

Organometallic chemistry is an organometallic compound study. Because many compounds without these bonds are chemically identical, an alternative may be compounds containing metallic bonds of a mostly covalent nature. Organometallic chemistry blends elements of inorganic chemistry with organic chemistry.

Transition Elements

A transition element may be defined as one which possesses partially filled d-orbitals in its penultimate shell. This conceptual definition is useful as it enables us to recognise a transition element merely by looking at its electronic configuration. This definition excludes zinc, cadmium and mercury from the transition elements as they do not have a partially filled d-orbital. 

However, they have also considered transition elements because their properties are an extension of the properties of transition elements in inorganic chemistry. In fact, the zinc group serves as a bridge between the transition elements and the representative elements.

The most notable characteristics shared by the 24 elements concerned are that they are all metals and that most of them are hard, solid and lustrous, have high melting and boiling points, and are good conductors of heat and electricity. The range in these properties is considerable; hence, the statements are comparable to the general properties of all the other elements.

Inorganic Chemistry Most Important Questions for JEE Main

Types of Reactions and Examples

There are about four types of chemical reactions in inorganic chemistry, namely combination, decomposition, single displacement and double displacement reactions.

Combination Reactions

As the name ‘Combination’ suggests, here, two or more substances combine to form a product which is called a combination reaction. For example,

Barium + F2 → BaF2

Decomposition reaction

It is a type of reaction where a single element splits up or decomposes into two products. For example,

FeS → Fe + S

Single Displacement Reactions

A reaction where a single atom of one element replaces another atom of one more element. For example,

Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq)

Double Displacement Reactions

This type of reaction is also called a ‘metathesis reaction’. Here, two elements of two different compounds displace each other to form two new compounds. For example,

CaCl2 (aq) + 2AgNO3 (aq) → Ca(NO3)2 (aq) + 2 AgCl (s)

What Are Polymers?

A polymer is a large molecule or a macromolecule which essentially is a combination of many subunits. The term polymer in Greek means ‘many parts’. Polymers can be found all around us, from the strand of our DNA, which is a naturally occurring biopolymer, to polypropylene which is used throughout the world as plastic.

Polymers may be naturally found in plants and animals (natural polymers) or maybe man-made (synthetic polymers). Different polymers have a number of unique physical and chemical properties due to which they find usage in everyday life.

Structure of Polymers

Most of the polymers around us are made up of a hydrocarbon backbone. A hydrocarbon backbone, being a long chain of linked carbon and hydrogen atoms, is possible due to the tetravalent nature of carbon.

A few examples of hydrocarbon backbone polymers are polypropylene, polybutylene, and polystyrene. Also, there are polymers which, instead of carbon, have other elements in their backbone. For example, Nylon contains nitrogen atoms in the repeated unit backbone.

Properties of Polymers

Physical Properties

• If chain length and cross-linking increase, the tensile strength of the polymer increases.
• Polymers usually change state from crystalline to semi-crystalline. Also, they do not melt.

Chemical Properties

• Compared to conventional molecules with different side molecules, the polymer is enabled by hydrogen bonding and ionic bonding resulting in better cross-linking strength.
• Dipole-dipole bonding side chains enable the polymer for high flexibility.
• Polymers with Van der Waals forces linking chains are known to be weak but give the polymer a low melting point.

Metallurgy

Metallurgy is defined as a process that is used for the extraction of metals in their pure form. The compounds of metals mixed with soil, limestone, sand, and rocks are known as minerals. Metals are commercially extracted from minerals at low cost and minimum effort. These minerals are known as ores. A substance that is added to the charge in the furnace to remove the gangue (impurities) is known as flux. Metallurgy deals with the process of purification of metals and the formation of alloys.

Extraction of Metals

The process of extracting metal ores buried deep underground is called mining. The metal ores are found in the earth’s crust in varying abundance. The extraction of metals from ores is what allows us to use the minerals in the ground. The ores are very different from the finished metals that we see in buildings and bridges. Ores consist of the desired metal compound and the impurities and earthly substances called Gangue. The extraction of metals and their isolation occurs over a few major steps:

• Concentration of ore
• Isolation of metal from concentrated ore
• Purification of the metal

Metallurgy Process: Important Principles to Remember

The metallurgical process can be classified as the following:

1. Crushing and grinding: The first process in metallurgy is crushing ores into a fine powder in a crusher or ball mill. This process is known as pulverisation.
2. The concentration of ores: The process of removing impurities from ore is known as a concentration of minerals or ore dressing. In metallurgy, we concentrate on the ores mainly by the following methods.
3. Hydrolytic method: In this method, we pour the ore over a sloping, vibrating corrugated table with grooves. A jet of water is allowed to flow over the surface. The denser ore particles settle in the grooves, and the impurities are washed away by water.
4. Magnetic separation: In this case, the crushed ore is placed on a conveyor belt. This belt rotates around two wheels, in which one of the wheels is magnetic, and therefore the magnetic particles get attracted to the magnetic wheel and fall apart from the non-magnetic particles.
5. Froth floatation: In this process, we take the crushed ore in a large tank that contains oil and water. A current of compressed air is passed through it. The ore gets wet by oil and is separated from the impurities in the form of froth. Ore is lighter, so it comes on the surface, and impurities are left behind.
6. Roasting and calcination: In metallurgy, the process of heating a concentrated ore in the presence of oxygen is known as roasting. This process is applied in the case of sulfide ores. For ores containing carbonate or hydrated oxides, heating is done in the absence of air to melt the ores, and this process is known as calcination.

Periodic Table

The periodic table is an arrangement of all the elements known to man in accordance with their increasing atomic number and recurring chemical properties. They are assorted in a tabular arrangement wherein a row is a period, and a column is a group.

Elements are arranged from left to right and top to bottom in the order of their increasing atomic numbers. Thus,

• Elements in the same group will have the same valence electron configuration and hence, similar chemical properties.
• Whereas, elements in the same period will have an increasing order of valence electrons. Therefore, as the energy level of the atom increases, the number of energy sub-levels per energy level increases.

The first 94 elements of the periodic table are naturally occurring, while the rest, from 95 to 118, have only been synthesised in laboratories or nuclear reactors.

Periodic Classification of Elements Characteristics

In the long-form periodic table, the elements are arranged in the order of their atomic numbers. An atomic number of an element is equal to the number of protons inside the nucleus of its atom.

The general features of the long-form periodic table are listed below:

• There are, in all, 18 vertical columns and 18 groups in the long-form periodic table.
• These groups are numbered from 1 to 18, starting from the left.
• There are seven horizontal rows called periods in the long-form periodic table. Thus, there are seven periods in the long-form periodic table.
• The elements of Groups 1, 2 and 13 to 17 are called the main group elements. They are also called typical or representative, or normal elements.
• The elements of Groups 3 to 12 are called transition elements.
• Elements with atomic numbers 58 to 71 (Ce to Lu), occurring after lanthanum (La), are called lanthanides. Elements with atomic numbers 90 to 103 (Th to Lw) are called actinides. These elements are called f-block elements and also inner transition elements.

Hydrogen

Hydrogen is the first element in the periodic table with atomic number one, which means it is the simplest and lightest element. Hydrogen is denoted by the symbol H. Hydrogen is nonmetallic, except at extremely high pressures, and readily forms a single covalent bond with most nonmetallic elements, forming compounds such as water and nearly all organic compounds. Hydrogen plays a particularly important role in acid-base reactions because these reactions usually involve the exchange of protons between soluble molecules.

Properties of Hydrogen

Physical Properties of Hydrogen

1. Colourless, odourless, neutral gas
2. Less soluble in water
3. Highly inflammable
4. Burns with a blue flame
5. Very low boiling points

Chemical Properties of Hydrogen

1. Dihydrogen is relatively inert at room temperature because of the strong bond enthalpy of the H–H bond.
2. Atomic hydrogen is produced under a high electric arc.
3. Its orbit is incomplete with a single electron.
4. Hydrogen combines with almost every element.

Isotopes of Hydrogen

Hydrogen shows three isotopes:

• Protium, which has zero neutrons
• Deuterium, which has one neutron
• Tritium, which has two neutrons

Allotropes of Hydrogen

Molecular hydrogen occurs in two isomeric forms.

1. Ortho-Hydrogen: In this type, two proton nuclear spins are aligned parallel.
2. Para-Hydrogen: In this type, two proton nuclear spins are aligned antiparallel.

Environmental Chemistry

Environmental chemistry deals with the study of reactions, sources, transport, and effects, along with the fates of all the chemical species present in the soil, water, and air, as well as the effects of technology thereon. One can define environmental chemistry as the branch of chemistry which deals with the study of the origin, transport, reactions, effects and fates of chemical species in the environment. It also includes the application of chemistry for understanding and solving environmental changes, phenomenon and their effect on organisms. It also includes the application of chemistry to solve problems related to the environment, such as environmental pollution.

A large number of substances (both toxic and non-toxic) are being added to the environment by both natural events and human activities daily. These substances, which are going continuously into the environment due to undesirable consequences of modern civilisation, industrialisation and excessive use of natural resources, bring about undesirable changes in our environment and adversely affect the life process of both animals and plants. 

Some important aspects of environmental chemistry cover the following topics:

• Environmental pollution: Atmospheric, water, and soil.
• Atmospheric pollution: Tropospheric and stratospheric.
• Gaseous pollutants: Oxides of carbon, nitrogen, sulfur, and hydrocarbons; their sources, harmful effects, and prevention.
• Greenhouse effect and global warming, acid rain.
• Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects, and prevention.
• Stratospheric pollution: Formation and breakdown of ozone, depletion of the ozone layer, its mechanism and effects.
• Water Pollution: Major pollutants such as pathogens, organic wastes, and chemical pollutants; their harmful effects and prevention.
• Soil pollution: Major pollutants such as pesticides (insecticides, herbicides and fungicides), their harmful effects and prevention.
• Strategies to control environmental pollution.

Inorganic Chemistry Phase 1 Important Questions

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