Studying various areas of science within the framework of a school or university course, it is easy to notice that they very often operate with the concept of matter.
But what is matter in physics and chemistry, what is the difference between the definitions of these two sciences? We will try to consider in more detail.
What is substance in physics?
Classical physics teaches that the matter of which the Universe is composed is in one of two basic states – in the form of matter and in the form of a field. A substance in physics is called matter, consisting of elementary particles (mostly neutrons, protons and electrons) that form atoms and molecules that have a rest mass other than zero.
Substance is represented by various physical bodies with a number of parameters that lend themselves to objective measurements. At any time, you can measure the specific gravity and density of the test substance, its elasticity and hardness, electrical conductivity and magnetic properties, transparency, heat capacity, etc.
Depending on the type of substance and external conditions, these parameters can vary within a fairly wide range. At the same time, each type of substance is characterized by a certain set of constant characteristics that reflect its quality indicators.
Aggregate states of substances
All substances existing in the Universe can be in one of the aggregate states:
– in the form of gas;
– in the form of a liquid;
– in a solid state;
– in the form of plasma.
At the same time, many substances are characterized by transitional, or borderline states. The most common ones are:
– amorphous, or glassy;
– liquid crystal;
– highly elastic.
In addition, some substances under special external conditions can pass into states of superfluidity and superconductivity.
What is a substance in chemistry?
Chemical science studies substances consisting of atoms, as well as the laws by which substances are transformed, called chemical reactions. Substances can be in the form of atoms, molecules, ions, radicals, and mixtures thereof.
Chemistry divides substances into simple ones, i.e. those that consist of atoms of the same kind, and complex ones, consisting of different types of atoms. Simple substances are called chemical elements: from them, like bricks, all substances in the world are composed.
In the course of a chemical reaction, substances interact with each other, exchanging atoms and atomic groups, as a result of which new substances are formed. At the same time, chemistry does not consider the processes in which changes occur in the atomic structure: the number and types of atoms participating in the reaction always remain unchanged.
All simple substances are summarized in the so-called periodic table of elements, which was created by the Russian scientist D.I. Mendeleev. In this table, simple substances are arranged in ascending order of their atomic masses and are grouped according to their properties, which greatly simplifies their further study.
Organic and inorganic substances
In modern chemistry, the division of all substances into two main groups is accepted: inorganic and organic. Inorganic substances include:
– oxides – compounds of chemical elements with oxygen;
– acid – compounds consisting of hydrogen atoms and the so-called acid residue;
– salt – substances consisting of metal atoms and acid residue;
– bases, or alkalis – compounds consisting of a metal and a hydroxyl group or several groups;
– amphoteric hydroxides – substances with the properties of bases and acids.
There are also more complex compounds of inorganic elements. In total, there are up to half a million varieties of inorganic substances.
Organic substances are compounds of carbon with hydrogen and other chemical elements. For the most part, they are complex molecules made up of a large number of atoms. There are many types of organic substances, depending on their composition and molecular structure. In total, at the moment science knows more than 20 million varieties of organic substances.