Non-metals are elements that differ significantly in physical and chemical properties from metals. They could explain in detail the reason for their differences only at the end of the 19th century, after the discovery of the electronic structure of the atom. What is the feature of non-metals? What qualities are characteristic of their day? Let's figure it out.
Non-metals - what is it?
The approach to the separation of elements into metals and non-metals has long existed in the scientific community. The first in the periodic table is usually attributed to 94 elements. Mendeleev’s non-metals include 22 elements. In the periodic system, they occupy the upper right corner.
In its free form, non-metals are simple substances, the main feature of which is the absence of characteristic metallic properties. They can be in all aggregate states. So, iodine, phosphorus, sulfur, carbon are found in the form of solids. A gaseous state is characteristic of oxygen, nitrogen, fluorine, etc. Only bromine is a liquid.
In nature, non-metal elements can exist both in the form of simple substances and in the form of compounds. In an unbound form, sulfur, nitrogen, oxygen are found. In compounds, they form borates, phosphates, etc. In this form, they are present in minerals, water, rocks.
Difference from metals
Non-metals are elements that differ from metals in appearance, structure and chemical properties. They have a large number of unpaired electrons at the external level, which means that they are more active in oxidative reactions and more easily attach additional electrons to themselves.
A characteristic difference between the elements is observed in the structure of the crystal lattice. In metals, it is metallic. In non-metals, it can be of two types: atomic and molecular. The atomic lattice gives the substances hardness and increases the melting point, it is characteristic of silicon, boron, germanium. Chlorine, sulfur, and oxygen have a molecular lattice. It gives them volatility and low hardness.
The internal structure of the elements determines their physical properties. Metals have a characteristic luster, good conductivity of current and heat. They are solid, plastic, forged, have a small color range (black, shades of gray, sometimes yellowish).
Non-metals are liquid, gaseous or solid substances that do not exhibit luster and ductility. Their colors vary greatly and can be red, black, gray, yellow, etc. Almost all non-metals conduct poorly current (except carbon) and heat (except black phosphorus and carbon).
Chemical properties of non-metals
In chemical reactions, non-metals can play the role of both oxidizing agents and reducing agents. When interacting with metals, they take on electrons, thus exhibiting oxidizing properties.
Interacting with other non-metals, they behave differently. In such reactions, the less electronegative element manifests itself as a reducing agent; the more electronegative acts as an oxidizing agent.
With oxygen, almost all (except fluorine) non-metals manifest themselves as reducing agents. When interacting with hydrogen, many are oxidizing agents, subsequently forming volatile compounds.
Some elements of non-metals have the ability to form several simple substances or modifications. This phenomenon is called allotropy. For example, carbon exists in the form of graphite, diamond, carbine, and other modifications. Oxygen has two of them - ozone and oxygen itself. Phosphorus is red, black, white and metallic.
Non-metals in nature
In varying amounts, non-metals are everywhere. They are part of the earth's crust, are part of the atmosphere, hydrosphere, are present in the Universe and in living organisms. In outer space, the most common are hydrogen and helium.
Within the Earth, the situation is completely different. The most important components of the earth's crust are oxygen and silicon. They make up more than 75% of its mass. But the smallest amount falls on iodine and bromine.
In the composition of sea water, oxygen accounts for 85.80%, and for hydrogen - 10.67%. Its composition also includes chlorine, sulfur, boron, bromine, carbon, fluorine and silicon. In the atmosphere, primacy belongs to nitrogen (78%) and oxygen (21%).
Non-metals, such as carbon, hydrogen, phosphorus, sulfur, oxygen and nitrogen, are important organic substances. They support the vital activity of all living things on our planet, including humans.