Physical properties of substances
The more time passes after graduation from a school or institute, the more forgetful is the fact that we were taught there. Today, few people remember what physical properties of substances are.
Substances simple and complex
Substances consisting of atoms of one element andwhich can not be further decomposed by a chemical reaction, are called simple. On the earth there are more than 400 kinds of simple substances. In most cases, the names of simple substances and the corresponding chemical elements coincide. Exceptions are oxygen and its allotropic modification of ozone, and carbon (diamond, graphite, carbine).
Complex substances or compounds consist of two or more chemical elements, which are connected in a certain proportion. Complex substances can be decomposed into simpler ones by chemical reaction.
Physical properties
Each substance is inherent only to itproperties that do not depend on the impact on it of other substances and elements. These are the physical properties of the substance; they include: aggregate state, crystal structure, boiling point, melting point, density, viscosity, thermal conductivity, heat capacity, electrical conductivity, dielectric constant. And also concentration, absorption, color, inductance, radioactivity, fluidity and emission.
As an example, consider sodium-alkalimetal is silvery white, plastic, soft, easily cut with a knife. Sodium has sufficiently high values of thermal conductivity and electrical conductivity, has a density of 0.96842 g / cm3, melts at a temperature of 97.86 ° C, begins to boil at a temperature of 883.15 ° C. These are the physical properties of sodium.
As a comparison, consider the physicalproperties of mercury of a heavy liquid metal of silvery-white color. Mercury has a melting point of -39 ° C, boils at a temperature of 356.58 ° C, and has a high thermal conductivity. The density of mercury at room temperature is 13.5457 g / cm23, this is the heaviest of all known liquids. Mercury has such physical properties.
As a result, based on the physical properties of simple substances, you can conduct a comparative analysis of various elements.
