|University Federico II
of Naples, Italy
Chemistry is evidence based. All chemical statements are based on experiment.
Chemistry is part of the body of modern science. It shares the experimental method of all sciences. It improves in time also using new discoveries and concepts from other sciences.
In turn, it provides both theoretical and experimental tools to different sciences. Biology, Geology cannot be studied without a thorough understanding of chemical phenomena.
We are generally interested in chemistry of substances in water solution. However, different environments have their own chemical substances and reactions: oilfields, high-pressure deep rocks, interstellar space.
Chemistry is often associated in the media with pollution and hazard. Actually, Chemistry is the science of all substances and their transformations. This includes the most precious things in our environment: air, water, mountains, earth, our own bodies and those of all living beings.
Chemistry is the science of oil spills, of acid rains, of metal pollution. It is also the science of fresh water, of air breathing, of the colours of butterfly wings.
Chemistry is the basis of our power on the surrounding world. It is the key to get the products that make our way of life possible. Of course, such a great power is also a great risk. A deep knowledge of Chemistry and its impact is necessary to seek the optimal trade-off between risks and advantages, and to take the decisions to effectively work.
A common representation of an atom. Modern views on atomic structure are very different from this simple figure.
Atomic theory is one of greatest achievements of modern Science.
Atomic theory was developed in the 19° century, as soon as the laws of Chemistry became clear and required a general explanation.
The original evidence for developing Atomic theory was the constant ratios of elements in compounds. This is very hard to explain unless we accept that matter is made of non divisible particles, ATOMS.
Some wide range ideas pervade Chemistry. One is that observed properties of matter should be understood and explained at atomic scale, i.e. in terms of very small particles, atoms and molecules.
The laws of Physics, that we have known for centuries, do not apply at atomic scale. For any discussion of atomic and molecular properties we must think in terms of quantum mechanics.
The properties and behaviour of substances depend not only on what kind of atoms (elements) they are made of, but even more on the way atoms are bonded to each other. The shape of molecules is the object of stereochemistry.
Chemistry is a complex subject: girls and boys start studying it in school. Further study is taken in the University, at different levels, depending on primary interests of students.
Chemistry is one subject, but it can be approached in many ways. It is customary to part it into several branches:
- Organic chemistry is concerned with Carbon compounds. Carbon forms an enormous number of compounds. The concept of functional groups helps to arrange such compounds in a coherent frame.
- Inorganic chemistry covers all the other elements. Organometallic chemistry studies compounds including organic molecules and metal atoms.
- Physical chemistry is concerned with general laws in structure, reactions and equilibria. It also covers interactions of matter with light and other physical agents, and provides techniques to investigate such subjects.
- Analytical chemistry tries to answer the questions that people most often put to chemists: What is therein? (qualitative analysis) and How much is it? (quantitative analysis).
- Biological chemistry (or Biochemistry) studies the chemistry of living beings. Biochemists exploit concepts and tools from all branches of Chemistry and apply them to the very special phenomenon of Life and to whole classes of molecules that are found only in the framework of Life.