We explain what metals are, how they are classified and the properties they have. Also, what are its characteristics, examples and more.
What are metals?
Metallic elements are those that are solid at room temperature (except mercury). In addition, they are good conductors of heat and electricity .
Metallic elements are the most abundant in the earth's crust : of the 118 elements that make up the Periodic Table, only 25 are non-metallic. They are usually found naturally in proportions of greater or lesser purity, forming part of minerals from the earth's subsoil, from which they must be separated.
The study and use of metals by humans , through physical processes of mixing, casting and molding , is known as metallurgy. It is one of the main foundations of engineering.
Classification of metals
Metallic elements are classified into different types, as they appear in the Periodic Table. Each group presents exclusive properties.
Alkali metals . They are located in group 1 of the Periodic Table. They are shiny, soft and very reactive under normal pressure and temperature conditions , which is why they are always forming chemical compounds and never free. They have low densities and are good conductors of heat and electricity.
Alkaline earth metals . They are located in group 2 of the Periodic Table. Its name comes from the fact that its oxides (formerly called "earths") have alkaline properties. They are harder and less reactive than alkaline, bright and good conductors of heat and electricity, as well as having low density and often colors.
Transition metals . They are located in the groups that go from 3 to 12 of the Periodic Table. Most metals are transitional. Most of them are hard, have high melting and boiling points, and are also conducive to heat and electricity.
Lanthanides . They are located in period 6 of the Periodic Table. Called lanthanoids or "rare earths", they form the "internal transition elements" together with actinides. They are elements that are very similar to each other and are very abundant on the earth's surface. They have unique magnetic behaviors.
Actinides . They are located in period 7 of the Periodic Table. They are metals of high atomic numbers, many of them have all their radioactive isotopes. Some are extremely rare in nature.
Transactinides . These are "super heavy" metals, which exceed the heaviest actinide in atomic number: lawrence (Z = 103). All of its isotopes have a very short half-life, since they are highly radioactive and are obtained only by synthesis in a laboratory.
Physical properties of metals
Metals have particular physical properties, such as:
Malleability . Many metals, when subjected to compression, can form thin, homogeneous sheets of the same material .
Ductility . Many metals, when subjected to traction, form homogeneous wires or strands of material.
Tenacity . Many metals are capable of resisting fracture, when subjected to sudden forces such as bumps or falls. The tougher a metal is, the less prone to breaking it will be.
Mechanical strength . Many metals are capable of withstanding traction, compression, torsion, and other similar forces without yielding their physical structure (deforming).
Conductivity . Metals are capable of allowing a current of electrons to pass through their surface (electricity) or of thermal energy (heat).
They are good thermal and electrical conductors.
They have high densities.
They are generally solid at room temperature (with the exception of mercury).
Almost all of them reflect light (photons), which gives them a very distinctive glow.
Chemical properties of metals
They form cations (positively charged ions).
Most form oxides when combined with oxygen.
Alkali metals generate explosions when they come into contact with water.
The hardness of metals is due to a type of atomic bond characteristic of their natural formations . It is about the metallic bonds (between atoms of the same metallic element).
These metallic bonds hold together the atoms of the same type of metal , forming regular structures of definite shape and, generally, solid. Atoms bonded in this way allow the free movement of electrons to and from neighboring atoms (as in an electron cloud), which is why metals are such good electrical and thermal conductors.
What are metals for?
Metals have been useful to mankind since ancient times . Their physical properties make them ideal for creating strong and resistant tools, statues or architectural structures of all kinds.
Due to their mechanical resistance, they have been used to manufacture machines and parts resistant to large amounts of force. From spears and shields to backhoes and personal computers , metals have been fundamental elements in the development of modernity .
On the other hand, their brilliance makes them ideal for forging jewelry and ornaments , at least as far as precious metals are concerned. The same happens with their good conduction of electricity, which makes them indispensable in electronic and computer systems.
Biological importance of metals
Metals are not organic elements, that is, they are not a direct part of the molecular structures of life (as some non-metals are). However, they are essential for the continuity of life , since many organic reactions require them and their exclusive properties.
For example, the nervous and neural systems require conductive metals , such as lithium and iron, although in very modest proportions. In the same way, the conduction of oxygen in the blood is thanks to hemoglobin, a protein that has iron atoms.
Alloys are homogeneous mixtures of metals . In them, no chemical reaction occurs and, therefore, there is no formation of new chemical compounds. On the other hand, each alloy adds the properties of the different components of the mixture .
Alloys are physical methods of combining metals and non-metals, carried out at high temperatures. This is how new materials are obtained, for example:
Steel . Alloy of iron and carbon and other elements to a lesser extent.
Bronze . Copper -tin alloy .
Brass . Alloy zinc and copper.
Duralumin . Alloy aluminum and copper.
Stainless steel . Nickel and chromium are added to the steel alloy.
Also known as semimetals, these are elements that have an intermediate behavior between metals and non-metals , and have properties of both. For example, they are better conductors than non-metals, but worse than metals. Also, they tend to mimic the reaction of metals when they come together with non-metallic atoms.
They are metalloids: boron (B), silicon (Si), germanium (Ge), arsenic (As), tellurium (Te), polonium (Po) and antimony (Sb).
Differences between metals and non-metals
Non-metallic elements are essential for organic life and belong, for the most part, to the so-called halogens , noble gases and other diverse groups of the Periodic Table. They differ from metals because:
They are not good conductors of heat or electricity.
They are not brilliant.
They can form both covalent and ionic bonds.
They are brittle, so they cannot be stretched to form wires, nor can they be compressed to form sheets.
In its early stages, the universe was made up of hydrogen and helium , two light gases . These two gases fuse in nuclear reactions in the centers of stars . As a consequence, enormous amounts of energy are produced and heavier atomic nuclei are also composed of new stable elements. This is how metallic elements gradually formed in the hearts of stars.
These heavy elements, like iron (Fe), pile up inside the stars . Its presence slows down the atomic reaction as it runs out of fuel, causing the death of the star. When it finally explodes (a supernova), it sends these elements to the various corners of the galaxy around it.
In a more terrestrial environment, we know that metals come from inside our planet . The Earth's core , for example, is made of pure iron and nickel.
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