There are topics that closely interconnect knowledge from various scientific disciplines of the natural profile. One of them refers to the concept of physical substance. From the point of view of chemistry, we are talking about the main form of matter, capable of interaction and transformation into various states, but retaining its elemental composition in the form of atoms and molecules. Physics considers deeper aspects of the structure of compounds and allows the decay of electrically neutral particles into the smallest components: protons, neutrons, electrons, etc. You should consider examples of physical substances as objects of chemical transformations, and dwell on a detailed description of their properties.
Types of existence of matter
The classification adopted in modern science distinguishes three material forms: field, substance and plasma. In the process of evolution, man has best adapted to the perception by his analyzers, primarily tactile, of various types of compounds that form animate and inanimate nature. Knowing their properties, he created a whole science - chemistry, with the help of which metallurgy arose, then the oil and gas industry. At the same time, organic chemistry was born, followed by the era of artificially created substances (drugs, synthetic fibers, ceramites, dyes and plastics). These organic substances, whose physical properties were very different from natural compounds, allowed man to subjugate the depths of the ocean, conquer new continents and step into space.
What do chemical compounds consist of?
Thanks to the scientific works of M.V. Lomonosov and John Dalton, it became known that atoms are the basis of matter. It is they who, combining in various types and quantities, form molecules, and those, in turn, form hundreds of thousands of substances from which the visible part of the real world is formed. In science, it is customary to divide compounds into two forms: simple and complex. The first of them includes oxygen (O 2) , carbon (C), magnesium (Mg), etc. They consist only of atoms of one chemical element.
The physical properties of a simple substance depend, first of all, on its state of aggregation, and it is determined by the type of chemical bond and the features of the crystal lattice. For example, the hardest substance in nature is diamond, which has an atomic crystal lattice. It determines its main physical characteristics: a very high melting point, thermal conductivity, as well as the ability to refract light rays and luminesce better than other natural materials.
Simple gaseous compounds
It’s hard to find someone who’s never heard of oxygen. Under normal conditions, it is a gas that is slightly heavier than air, odorless and colorless. At low temperatures, of the order of –183 ° and atmospheric pressure, the compound changes its state of aggregation, passing into a liquid.
In this case, oxygen has a new physical property: it can be attracted by a magnet. The physical properties of a solid, for example, such as graphite, are also due to the structure of its crystal. It has the same formula as diamond, but completely different characteristics. So, the atoms in its crystal lattice are arranged in layers, the distance between which is large. Therefore, the connection itself is quite soft and leaves a scaly mark on the surface or paper. Graphite is greasy to the touch and conducts electric current, which is why it is widely used in the semiconductor industry and for the manufacture of electrodes.
Travel to the country of organic chemistry
To understand what organic matter is, the physical properties of which are studied even at school, you must first find out the features of their structure. It turns out that they all contain carbon atoms that are in an excited state and exhibit a valence of four. Moreover, the physical and chemical properties of the compounds depend on the spatial arrangement of the carbon particles. Isomerism is a phenomenon found only in organic chemistry.
Two or more compounds can have the same molecular formula, but completely different properties. For example, methylpropane and butane differ in boiling points, but their formula is the same - C 4 H 10 . Examples of physical properties of substances related to isomers confirm the fact of their dependence on the structure of the molecule and the structural formula. The reason for isomerism lies in the different spatial configuration of the carbon skeleton of the molecule. All the features of such compounds were studied by the outstanding Russian scientist M. Butlerov, who created the theory of the structure of organic compounds.
New polymer features
Earlier, we mentioned that organic substances artificially created by humans have unique characteristics that have not been previously encountered in nature. We give examples of physical substances of organic origin obtained in the laboratories of scientists. So, styrene-butadiene rubbers are formed as a result of the polymerization reaction between vinylbenzene and butadiene. They have high wear resistance, elasticity and resistance to abnormally high and low temperatures. Such polymers are used to make automobile tires, conveyor belts, escalators, and lightweight microporous material for the shoe industry.
Phenol-formaldehyde plastics and their role
Polycondensation reactions carried out on an industrial scale, allow to obtain such compounds that become indispensable in many areas of industry. These include the products of the interaction between a cyclic hydrocarbon containing a hydroxyl group - phenol, and methanal. The reaction between them proceeds when heated using a catalyst (acid or alkali). Consider specific examples. Physical substances related to plastics are derived from phenol-formaldehyde resins.
What are Bakelites?
Materials derived from polymers are called phenoplasts or bakelites. These are raw materials for the production of parts in the engineering industry. Also, plastics are used as substitutes for products from non-ferrous and ferrous metals. Artificial materials have several advantages: they are resistant to abrasion, resistant to corrosion, light and durable. A wide range of products from phenol-formaldehyde plastics can be seen among household items: kitchen utensils, furniture, tableware and toys.
Physical and chemical substances
If the task is to get acquainted with such properties of compounds as density, hardness, boiling and melting points, then it is customary to talk about the characteristics of physical substances, which are considered mainly in the course of physics. Take metals for example. Their common properties are electrical and thermal conductivity. The lightest of them is lithium: its density is only 0.53 g / cm 3 , and the heaviest metal is osmium (22.6 g / cm 3 ).
Hardness is another property of physical substances. Here, chromium takes first place, since it is able to cut even glass. But sodium, potassium and cesium are so soft that they can be cut with an ordinary knife.
It is customary to talk about chemicals in the context of their ability to interact with other compounds. Chemistry studies these properties. Metals, for example, react with oxygen to form basic oxides. The most active of them interact with water, which leads to the appearance of alkalis: sodium, potassium, calcium hydroxides, etc.
So, examples of physical substances characterized by the ability to conduct heat and electric current, with density, hardness and other properties, were given above.