Inorganic Chemistry

Inorganic Chemistry

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Have you ever wondered about the science behind everyday items like car batteries, drain cleaner, and even tin cans? It's all thanks to inorganic chemistry! This branch of chemistry focuses on the structure, properties, and behavior of inorganic compounds. Essentially, it's the study of chemicals that don't contain carbon-hydrogen bonds. In this article, we'll give you an introduction to inorganic chemistry and compare it to organic chemistry. We'll also explore some key concepts and give you a sneak peek of what to expect in future articles. Get ready to dive into the fascinating world of inorganic chemistry!

What are inorganic compounds?

Now that we have a basic understanding of what inorganic chemistry is, let's take a closer look at inorganic compounds. Inorganic compounds are simply compounds that don't contain carbon. This definition may seem broad, but it's actually quite specific. It includes all of the other elements on the periodic table, from hydrogen to helium, nitrogen to nickel, and everything in between. Take a look at the periodic table below. You'll notice that carbon is highlighted in pink. In inorganic chemistry, we study compounds made from all the other elements, like halogens, transition metals, and more. So, if you're curious about the building blocks of our world, inorganic chemistry is the place to start!

Inorganic chemistry focuses on compounds that aren't carbon-based. Here carbon is shown in pink

It's important to note that inorganic chemistry doesn't completely ignore carbon. Rather, it focuses on compounds that don't contain carbon-carbon or carbon-hydrogen bonds, which are known as organic compounds. These are studied in organic chemistry, a related field. Inorganic chemistry, on the other hand, covers a wide range of substances, including carbon-containing structures like graphite and diamond.

Let's take a closer look at one of our earlier examples - car batteries. In diesel and petrol cars, the batteries are made up of electrodes placed in a solution of sulfuric acid. The positive electrode, called the anode, is coated in lead dioxide, while the negative electrode, called the cathode, is made from a grid of a lead alloy filled with sponge lead. In contrast, electric cars use batteries with a graphite anode, a mixed-metal oxide cathode, and a lithium-ion electrolyte. Inorganic chemistry plays a vital role in the development of all these substances and many more, from catalysts and paints to cleaners, jewelry, and drugs. So if you're interested in learning more about the science behind the things we use every day, inorganic chemistry is definitely worth exploring!

A simplified diagram of the battery in an electric car
A simplified diagram of the battery in an electric car

The basics of inorganic chemistry

Let's now look at some of the basic ideas you'll come across in inorganic chemistry.

The periodic table

The periodic table is a fundamental tool used in chemistry to organize and understand the properties of the elements. It is arranged in rows and columns based on atomic number and properties. The modern periodic table was created by Dmitri Mendeleev, a Russian chemist, who recognized patterns in the properties of elements and arranged them accordingly. He even left gaps for undiscovered elements which were later found and fit perfectly into his proposed structure.

The periodic table is organized into columns, known as groups, and rows, known as periods. Some noteworthy groups include the alkali metals (group 1), which are highly reactive and easily lose their outermost electron to form positively charged ions; and the halogens (group 7 or 17), which are highly reactive nonmetals that readily form negatively charged ions. The periodic table also displays periodicity, meaning that the properties of the elements repeat in a predictable pattern across each row or period. The periodic table is divided into blocks based on the electron configurations of the elements. The s-block includes the first two groups, which contain the alkali and alkaline earth metals. The p-block includes the last six groups, which contain the nonmetals and metalloids. The d-block contains the transition metals, which are known for their characteristic metallic properties such as luster and ductility. The f-block contains the lanthanides and actinides, which are sometimes referred to as the inner transition metals. The periodic table is a vital tool for chemists, as it provides a framework for understanding the properties and behavior of elements. By studying the periodic table, scientists can predict the chemical behavior of elements, design new materials, and better understand the natural world.

The periodic table, split into four blocks
The periodic table, split into four blocks


Ions are species formed when an atom loses or gains one or more electrons to form a charged particle. Cations are positive ions whereas anions are negative ions.

Oxidation states

You may have come across different species such as iron (II) and iron (III), which have different oxidation states. Oxidation states indicate the number of electrons that have been added to or removed from an element to reach its current state.

In redox reactions, which involve the transfer of electrons between species, oxidation states are crucial. They allow us to keep track of the electrons gained and lost by each species during the reaction. We can represent oxidation states using superscript numbers or Roman numerals, as in the case of iron (II) and iron (III). Iron (II) has an oxidation state of 2+ and can also be written as Fe2+. This means that it has lost two electrons compared to a neutral iron atom. Iron (III), on the other hand, has an oxidation state of 3+ and can be written as Fe3+. It has lost three electrons compared to a neutral iron atom. It's worth noting that oxidation states don't always correspond to the actual distribution of electrons within a species, but they're still a useful tool for understanding chemical reactions. By keeping track of oxidation states, chemists can predict the outcome of a reaction and design new materials with specific properties.


Redox, short for oxidation-reduction, is a term used to describe reactions where both oxidation and reduction occur. These reactions are essential in physical chemistry and also have significant applications in inorganic chemistry.

In a redox reaction, a species is oxidized when it loses electrons, and it is reduced when it gains electrons. Many inorganic compounds are formed through redox reactions. For instance, consider the reaction between zinc and copper sulfate:

Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

We can represent this as a redox reaction using oxidation states:

Zn(s) → Zn2+(aq) + 2e-

Cu2+(aq) + 2e- → Cu(s)

In this reaction, zinc is oxidized because it loses electrons, while copper is reduced because it gains electrons. Zinc acts as a reducing agent since it reduces copper, while copper acts as an oxidizing agent since it oxidizes zinc.

Redox reactions are important in inorganic chemistry since they allow us to synthesize new compounds and understand the behavior of elements and compounds. By analyzing redox reactions, chemists can predict the outcome of reactions and design new materials with specific properties.

Acids and bases

You also learn about acids and bases in physical chemistry, but they are relevant here as well. An acid is a proton donor whilst a base is a proton acceptor. Some elements and compounds are much better acids or bases than others, and you'll learn a bit more about that in inorganic chemistry.

Transition states

A transition state is a crucial stage in a chemical reaction where some bonds are partially broken, and new bonds are partially formed. This state represents the highest energy level of molecules, making transition states highly unstable.

To understand a transition state, imagine slowing down a chemical reaction and taking a snapshot halfway through. If we zoom in closely, we might see that some of the original bonds in the reactants have broken, but new bonds haven't fully formed yet, or that intermediate compounds have formed instead. This is an example of a transition state. Interestingly, not all molecules that start reacting together will go on to complete the reaction. At the transition state, there is an exact 50% chance of the reaction finishing. However, once a reaction has passed through the transition state, it will always go on to completion, according to transition state theory. Transition states play a critical role in chemistry, as they allow us to understand how reactions occur and design new reactions with specific properties. By understanding the behavior of molecules at the transition state, chemists can develop new strategies for synthesizing compounds and developing new materials.

The transition state of a reaction
The transition state of a reaction

Types of compound

Inorganic chemistry is a diverse field that covers a wide range of topics. Some of the key areas of study in this field include:

  1. Periodicity: This is the study of the periodic table and how the properties of elements vary in a periodic manner. It involves analyzing the trends in atomic size, ionization energy, and electronegativity, among others.
  2. Group 2 metals: This group includes elements such as beryllium, magnesium, and calcium. Inorganic chemists study their properties, including their reactivity, bonding, and uses.
  3. Halogens: These are elements in group 17 of the periodic table, such as fluorine, chlorine, and bromine. Inorganic chemists study their properties, including their reactivity, bonding, and uses.
  4. Ions: Inorganic chemists study the behavior of ions in solution, including their interactions with other ions and molecules. This includes topics such as acid-base chemistry, redox reactions, and precipitation reactions.
  5. Coordination compounds: These are compounds that contain a central metal ion surrounded by a group of atoms or molecules called ligands. Inorganic chemists study their properties, including their structures, bonding, and reactivity.

Overall, inorganic chemistry is a fascinating field that covers a wide range of topics and has many practical applications in industry, medicine, and materials science.

Periodicity and trends

Period 3 of the periodic table is unique because it contains a range of elements with varying properties. The elements in this period include:

  1. Sodium (Na): A soft, silvery-white metal that is highly reactive and easily oxidized in air.
  2. Magnesium (Mg): A strong, lightweight metal that is commonly used in alloys and as a structural material.
  3. Aluminum (Al): A lightweight, corrosion-resistant metal that is used in a wide range of applications, including packaging, construction, and transportation.
  4. Silicon (Si): A metalloid that is essential for the production of many electronic devices, including solar cells and computer microchips.
  5. Phosphorus (P): A non-metal that is essential for life and is used in fertilizers, detergents, and other industrial applications.
  6. Sulfur (S): A non-metal that is used in a wide range of applications, including the production of fertilizers, cosmetics, and medicines.
  7. Chlorine (Cl): A highly reactive non-metal that is used in water treatment, as a disinfectant, and in the production of many chemicals.
  8. Argon (Ar): A noble gas that is chemically inert and is commonly used in welding and other industrial processes.

Each of these elements has unique properties that make them useful in a variety of applications. Inorganic chemists study these properties to understand how the elements interact with each other and with other compounds, and to develop new materials and technologies based on these interactions.

Groups 2 and 7

Group 2 elements, also known as the alkaline earth metals, include beryllium, magnesium, calcium, strontium, barium, and radium. These elements have a similar electronic configuration, with two valence electrons, which makes them highly reactive. As you move down the group, the reactivity of the elements increases. Beryllium is the least reactive element in the group, while radium is the most reactive. This is due to the increasing size of the atoms and the decreasing ionization energy as you move down the group.

Group 2 compounds are generally basic and can form salts with non-metals. The solubility of group 2 compounds depends on the compound and the solvent used. For example, hydroxides and sulfates of group 2 metals are generally insoluble in water, while nitrates and acetates are generally soluble. Group 7 elements, also known as halogens, include fluorine, chlorine, bromine, iodine, and astatine. These elements have a similar electronic configuration, with seven valence electrons, which makes them highly reactive and able to form strong covalent bonds. Chlorine has the best oxidizing ability of all the halogens. This is due to its high electronegativity, which allows it to attract electrons from other atoms and molecules. Chlorine has many uses, including as a disinfectant for water and swimming pools, in the production of PVC, as a bleaching agent for textiles and paper, and in the production of many chemicals, including pharmaceuticals and pesticides. However, chlorine gas is highly toxic and can be lethal at high concentrations, so it must be handled with care.

Transition metals

Transition metals are a group of elements that have a partially filled d subshell in their atomic structure. These elements are located in the d block of the periodic table and are known for their distinctive properties, such as high melting and boiling points, variable oxidation states, and the ability to form complex ions and compounds.

Transition metals include elements such as iron, copper, silver, and gold. These elements have a variety of uses, such as in the production of steel, electrical wiring, coins, and jewelry. Not all d block elements are transition metals, as some, like zinc, have a full d subshell and do not form ions with a partially-filled d subshell. However, some f block elements are considered transition metals and are known as inner transition metals. These elements include the lanthanides and actinides, which are located in the f block of the periodic table. The unique properties of transition metals are due to their partially filled d subshell, which allows them to form complex ions and compounds with other elements. These compounds often have intense colors and are used in a variety of applications, including pigments, catalysts, and medicines. Overall, transition metals are an important group of elements with a wide range of uses and properties, and they continue to be an area of active research and discovery in the field of chemistry.

The periodic table, with the elements in the d and f blocks highlighted

Transition metals are a unique group of elements that possess several common properties. One of the most important properties of transition metals is their variable oxidation states. This means that they can exist in different ionic forms, depending on the conditions under which they are formed. For example, iron can exist in the +2 or +3 oxidation states, while copper can exist in the +1 or +2 oxidation states. Another common property of transition metals is their bright colors. This is due to the fact that they absorb light in the visible part of the electromagnetic spectrum, which gives them their characteristic hues. For example, copper compounds often have a blue or green color, while iron compounds can be yellow, orange, or red.

Transition metals are also known for their ability to act as good catalysts. This is because they have partially filled d orbitals, which allows them to interact strongly with other molecules and facilitate chemical reactions. For example, platinum is often used as a catalyst in the production of fertilizers and in catalytic converters in cars. Finally, transition metals have the ability to form complex ions with ligands, which are other species that bond to the metal using coordinate or dative covalent bonds. This ability to form complex ions is due to the partially filled d orbitals in the metal, which can accommodate the bonding electrons from the ligands. These complex ions often have distinctive properties, such as bright colors and magnetic behavior. Overall, the common properties of transition metals make them a unique and important group of elements, with a wide range of applications in industry, medicine, and everyday life.

Reactions of ions in aqueous solution

Inorganic chemistry is a vast field that covers a wide range of topics beyond what we have explored so far. One area of interest is the acidity of metals and how it relates to their properties. Some metals are better acids than others because of their electron configuration and ability to attract or donate electrons. Another important concept in inorganic chemistry is chelation, which refers to the binding of metal ions to organic molecules called chelating agents. This process can have a significant impact on the properties and reactivity of the metal ion, including its solubility, stability, and biological activity.

In ligand substitution reactions, water can be replaced by other ligands that bind to the metal ion more strongly. This process involves the displacement of the water molecule from the coordination sphere of the metal ion and the subsequent binding of the new ligand to the vacant coordination site. Other topics within inorganic chemistry include the properties and reactions of alkali metals, electrolysis, and the extraction of metals. It is important to note that different exam boards may focus on different topics in their inorganic chemistry curriculum, so it is essential to check the specific requirements for your course and exam. In summary, inorganic chemistry is a fascinating field that deals with the structure, properties, and reactivity of inorganic compounds. The topics covered in this field include periodicity, group 2 and group 7 elements, transition metals, and the acidity of metals, among others.

Frequently Asked Questions about Inorganic Chemistry

What is the difference between organic and inorganic chemistry?

Organic chemistry is a field that studies the structure, reactivity and properties of carbon-based molecules. In contrast, inorganic chemistry studies the structure, reactivity and properties of compounds that aren’t based on carbon.

Why is inorganic chemistry important?

 Inorganic chemistry plays a role in many areas of life. For example, we use inorganic chemistry to design and develop things like catalysts, paints, batteries, surfactants, cleaners, jewellery and drugs.

What does inorganic mean in chemistry? 

 Inorganic means not based on carbon. Whilst organic molecules are based around C-C and C-H bonds, inorganic compounds are based around all the other elements in the periodic table. Examples include salts and minerals.

What are some examples of inorganic chemistry?

Examples of inorganic compounds include salts, minerals, acids and metals. Examples of applications of inorganic chemistry include designing drugs, batteries, electronics and cleaning products.

Do mechanisms appear in inorganic chemistry?

Mechanisms do appear in inorganic chemistry but you won’t encounter them at this level of study.

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