What is Inorganic Chemistry ?
Definition of inorganic chemistry:
Inorganic Chemistry is the study of the structures, properties, and behaviours incl. reactions, of elements, mixtures e.g. in solutions, and chemical compounds that do not contain carbon-hydrogen bonds (such compounds are defined as 'organic' for the purposes of chemical classification so study of those compounds is considered organic chemistry).
In some subject-areas of study and research the distinction between organic and inorganic chemistry is unclear and is said to overlap. For example, organometallic chemistry (the study of chemical compounds whose molecules include bond(s) between carbon and a metal) includes aspects of both inorganic chemistry and organic chemistry. However, most (and often all) of the chemistry normally studied at school level may be clearly defined as either Organic or Inorganic Chemistry.
It is useful to be aware that most biological chemicals, i.e. those generated by plant or animal life, are organic because they include carbon-hydrogen bonds. However that is a very general observation and there are too many common exceptions to use it as a 'rule'. Some inorganic chemicals e.g. carbon dioxide (CO2) are also found and created by living things.
It is useful to understand what is inorganic chemistry in order to know which books or sections to use when researching chemistry questions, e.g. looking-up information in textbooks and via other sources and media.
As much of introductory (school-level) inorganic chemistry is concerned with the chemical elements, a convenient way to identify key topics within introductory inorganic chemistry is using the periodic table: The periodic table is structured in such a way as to group together elements whose structures follow certain patterns and so have particular properties in common.
Inorganic Chemistry Topics identifiable from the Periodic Table include the chemistry of the following elements, from left-to-right across the Periodic Table:
- Groups I and II
(of the Periodic Table), which are also known as the
- The elements of Group I are known as Alkali Metals, and include: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs), and the rare radioactive element Francium (Fr).
- The elements of Group II are known as Alkaline Earth Metals, and include: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and the rare radioactive element Radium (Ra).
- Transition Metals, which are also known as the d-block elements.
- Group III
This includes the non-metallic element Boron (B), Aluminium (Al), together with Gallium (Ga), Indium (In) and Thallium (Tl).
- Group IV
This includes the relatively common elements: Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn) and Lead (Pb).
Note that the element carbon is one of the most important elements in organic chemistry but also forms some compounds classified within inorganic chemistry, e.g. carbon monoxide (CO) and carbon dioxide (CO2).
- Group V
This includes: Nitrogen (N), Phosphorous (P), Arsenic (As), Antimony (Sb) and Bismuth (Bi).
- Group VI
This includes: Oxygen (O), Sulphur (S), Selenium (Se), Tellurium (Te) and the radioactive element Polonium (Po).
- Group VII,
which are known as the halogens.
This includes Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and the radioactive element Astatine (At).
- Group 0,
which are known as the
Noble Gases and, due to their inactivity,
also as 'inert gases'.
This includes Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and Radon (Rn).
Although the above indicates categories of elements, inorganic chemistry is not only about those elements - but also about how they react and the compounds they form. Inorganic chemistry is a huge subject area that includes all chemical reactions and compounds that are not or do not involve organic compounds (i.e. substances which have carbon-hydrogen bonds).
Alternatively, it may be easier to answer the question what is inorganic chemistry by defining what it is not:
That is - define chemistry as 'the science of matter' then say that inorganic chemistry concerns the chemical properties (as opposed to the physical chemistry) of non-organic chemical substances. Then you would, of course, have to say that the chemical properties, incl. reactions etc. of organic chemicals (which all contain carbon-hydrogen bonds) fall into the category of organic chemistry.
The following list is intended to provide a general overview of inorganic chemistry using very brief descriptions of some of the main topics to further explain what is inorganic chemistry. Note that it does not relate to any particular syllabus (e.g. for an age-group, level of study, or exam) and that other study materials may list different topics, similar topics under different headings, and/or place them in a different order.
Examples of other Key Topics in the field of Inorganic Chemistry:
- Descriptive Inorganic Chemistry
This concerns classification of compounds based on their properties.
It uses the position in the periodic table of the heaviest element in the compound (i.e. the one with the highest atomic weight), and also involves grouping compounds according to their structural similarities. Examples of classifications within descriptive inorganic chemistry include co-ordination compounds, "main group" compounds, transition metal compounds, cluster compounds, bioinorganic compounds and solid state compounds.
This area of inorganic chemistry can be thought of as an extension of the knowledge of the elements mentioned in the sections above into the systematic description of inorganic compounds.
- Basic (General) Types of Inorganic Chemistry Reactions
- Combination Reactions (two or more substances combine to form a single chemical substance)
- Decomposition Reactions (the opposite of "combination reactions", i.e. a substances decomposes into its chemical parts)
- Single Displacement Reactions (an atom or ion that forms part of a single compound is replaced by an atom or ion of a different element)
- Double Displacement Reactions (elements from two different compounds displace each other to form compounds not present at the start of the reaction and which are due to different combinations of the elements present in the original compounds)
- Chemistry of Inorganic Compounds,
e.g. Chemistry of Salts
Salts are ionic compounds, some of which can form large crystal structures composed of cations (positively charged ions) and anions (negative ions). There are many different salts. Common simple examples include sodium chloride (NaCl), potassium chloride (KCl), calcium carbonate (CaCO3) and sodium bicarbonate (NaHCO3).
Note that although there are many inorganic salts, there are also some organic salts - which would of course be classified within the field of organic chemistry.
Study of the chemistry of the earth's natural environment is important for understanding the planet and managing its resources. Much of geochemistry is inorganic chemistry because so many elements are found in the solid rocks that form the earth's crust.
- Extraction (incl. Mining) of Inorganic Chemicals
Inorganic compounds are found in nature as minerals. A huge variety of metal ores and other minerals are extracted using various techniques from locations in particular parts of the world (some minerals are only found in certain places) for all sorts of specific purposes, e.g. in jewellery, construction, semi-conductors, agriculture, pharmacology, and other industries.
- Bioinorganic Chemistry
Most of biochemistry concerns organic compounds, e.g. amino acids.
Bioinorganic chemistry includes study of certain elements (often referred to as "minerals") that are essential for life, knowledge of the chemistry of elements that form important biological molecules, e.g. bio macromolecules, of other elements that have important roles in biological systems, and of course understanding of the chemistry of toxic substances.
- Synthetic Inorganic Chemistry
Some inorganic chemicals can be obtained or purified from nature, others are synthesised in industrial chemical plants (i.e. on large scales) and/or in laboratories (usually on relatively smaller scales).
- Industrial Inorganic Chemistry
The term industrial chemistry can refer to various large-scale processes and research areas.
Many aspects of industrial science involve work in the field of inorganic chemistry.