All chemical elements can be conditionally divided into non-metals and metals. Do you know how they differ? How to determine their position in the table of chemical elements? You will find answers to these and other questions in our article.
Position of non-metals and metals: periodic table
It is not always possible to find out which group a chemical element belongs to by external signs and physical properties. The properties of metals and non-metals can be determined by their location in the periodic table.
To do this, you need to visually draw a diagonal from boron to astatine, from 5 to 85 numbers. In the upper right corner will be predominantly non-metals. There are a minority of them in the table, only 22 elements. Metals are on the right side of the periodic table at the top - mainly in groups I, II and III.
Differences between non-metals and metals are initially due to the structure of their atoms. Let's start with the number of electrons in the outer energy level. For metal atoms, it varies from one to three. As a rule, theyhave a large radius, so metal atoms quite easily give up outer electrons, as they have strong reducing properties.
Non-metals have more electrons at the outer level. This explains their oxidative activity. Non-metals add missing electrons, completely filling the energy level. The strongest oxidizing properties are exhibited by non-metals of the second and third periods of groups VI-VII.
A filled energy level contains 8 electrons. Halogens with valence I have the highest oxidizing power. Fluorine is the leader among them, since this element has no free orbitals.
Structure of metals and non-metals: crystal lattices
Physical properties of substances are determined by the arrangement of elementary particles. If you conditionally connect them with imaginary lines, you get a structure called a crystal lattice. Its nodes can contain different structures: atoms, molecules or charged particles - ions.
In some non-metals, an atomic crystal lattice is formed, the particles of which are connected by covalent bonds. Substances with this structure are solid and non-volatile. For example, phosphorus, silicon and graphite.
In the molecular crystal lattice, the bond between elementary particles is weaker. Usually, such non-metals are in a liquid or gaseous state of aggregation, but in some cases they are solid, low-melting non-metals.
In any metal sample, some of the atoms lose their outerelectrons. At the same time, they turn into positively charged particles - cations. The latter recombine with electrons, forming neutrally charged particles - cations, electrons and atoms are simultaneously located in the metal lattice.
Let's start with the state of aggregation. It is traditionally accepted that all metals are solids. The only exception is mercury, a viscous silvery liquid. Its vapors are a contaminant - a toxic substance that causes poisoning of the body.
Another characteristic feature is the metallic luster, which is explained by the fact that the surface of the metal reflects light rays. Another important feature is electrical and thermal conductivity. This property is due to the presence of free electrons in metal lattices, which in an electric field begin to move in a direction. Mercury conducts heat and current best of all, silver has the lowest performance.
Metal bond causes malleability and ductility. According to these indicators, gold is the leader, from which it is possible to roll out a sheet as thick as a human hair.
Most often, the physical properties of metals and non-metals are opposite. So, the latter are characterized by low rates of electrical and thermal conductivity, the absence of metallic luster. Under normal conditions, non-metals are in a gaseous or liquid state, and solids are always brittle and fusible, which is explained by the molecular structure of non-metals. Diamond, red phosphorus and silicon are refractory andnon-volatile, these are substances with a non-molecular structure.
What are semimetals
In the periodic table between metals and non-metals there are a number of chemical elements that occupy an intermediate position. They are called semimetals. Atoms of semimetals are linked by a covalent chemical bond.
These substances combine the features of metals and non-metals. For example, antimony is a silvery-white crystalline substance and reacts with acids to form s alts, typical metallic properties. On the other hand, antimony is a very fragile substance that cannot be forged, and it can even be crushed by hand.
So, typical non-metals and metals have opposite properties, but the division is rather arbitrary, since a number of substances combine both features.