METALS: HISTORY, PROPERTIES, TYPES, USES, EXAMPLES - CHEMISTRY - 2025

The metals are formed by a group of elements that are located on the left side, with the exception of the nonmetal hydrogen, of the Periodic Table. Metals constitute about 75% of the chemical elements, so it can be said that a large part of nature is metallic in nature.

The metals that man initially processed in prehistory were the following: gold, silver, copper, tin, lead and iron. This was due to the fact that they were in their native state or because they were easy to process to make useful objects.

Metallic elements in blue color. Metalloids in green and non-metals in brown

It seems a thing of magic that from piles of rocks and minerals, shiny and silver bodies can be extracted (with certain important and outstanding exceptions). Such is the case of bauxite and aluminum, from whose clay rocks this reduced metal is obtained in sheets or silver papers.

Metals are the framework of industries; its cabling, reactors, units, containers, all in some way or another are made up of metals and their alloys.

The first coins, weapons, tools, armor were made with metals, to later be used in the manufacture of vehicles, bicycles, boats, airplanes, computers, among other essential objects in modern life.

History

Copper Age

Metallurgical expansion - Source: Metallurgical diffusion.svg under the Creative Commons Attribution-ShareAlike 4.0 International license

In 9000 BC, the first forged copper metal objects were made in the Near East, when man discovered that hammering copper increased its strength and resistance, using it to make knives. This is the Copper Age.

It was discovered that copper could be obtained by heating blue minerals, such as corvellite and malachite (4000-3000 BC).

The Chalcolithic period is a period of time that precedes the Bronze Age, corresponding to 5,000-3,000 BC. Man began to experiment with the fusion and smelting of copper, in order to obtain copper forged from copper oxide.

Bronze Age (3,000-1,500 BC)

Materials from the Bronze Age - Source: Gaguilella under the Creative Commons Attribution-ShareAlike 4.0 International license.

Man probably accidentally began making alloys, initially of copper and arsenic, and later with copper and tin, to obtain bronze in the Near East.

The bronze articles, corresponding to this time, had 87% copper, 11% tin, and small amounts of iron, arsenic, nickel, lead and antimony.

Iron Age (700 BC)

The man used his experience in the production of wrought copper for the production of wrought iron in the Near East. In that same period of time the granulation of Etruscan powder occurred, Italy.

The earliest known production of steel, an alloy of iron and carbon, was manifested in pieces of the metal at an archaeological site in Anatolia (1800 BC)

Around AD 1122, at an unknown date and place, cast iron was introduced. In 1440 AD the Great Bell of Beijing, China, was produced. Almost three centuries later, in 1709 AD, molten iron is produced using coke as a fuel material.

In 1779, cast iron was used in England as an architectural material. In 1855, Henry Bessenir used pig iron as a raw material to obtain mild steel. The English Clark and Wood (1872) patented an alloy, currently considered as stainless steel.

Physical properties of metals

The bronze of these ancient bells demonstrates the usefulness of metals for ornamental or religious purposes. Source: Pxhere.

Among some physical properties of metals we have:

-Metals are shiny in appearance and are able to reflect light.

-In general, they are good conductors of electricity and heat.

-They have high melting and boiling points.

-They are malleable, that is, they can be hammered to produce thin sheets.

-They are ductile, with them you can manufacture wires or fibers of very small diameter.

-They are presented in solid state, except for mercury, which is in liquid state at room temperature, and gallium, which melts just by squeezing it between your hands. In the following image you can see a container of mercury:

-They are opaque bodies, their thin sheets are not crossed by light.

-They are very hard, except for sodium and potassium, which can be cut by a knife.

-They have a high density, with osmium and iridium having the highest density, and lithium having the lowest density.

Chemical properties of metals

Among some of the chemical properties of metals we have:

-They tend to lose electrons and form metal cations, M ^{n +}, where n indicates their oxidation number, which only for alkali and alkaline earth metals coincides with their valence number.

-Its electronegativities are low.

-They corrode and experience oxidation damage.

-Forming basic oxides when reacting with oxygen. These oxides when combined with water form metal hydroxides. Metal oxides react with acids to form salts and water.

-They are good reducing agents, since they give up their electrons.

Metal types

Metals are classified into the following: alkaline, alkaline-earthy, post-transitional, transitional and the so-called rare earths.

Alkali metals

They are not usually found free in nature because they oxidize easily. They have a suborbital s ¹ in their outer orbital shell, so they have a +1 oxidation state. They are metals that react exothermically with water and are strongly reducing.

Alkaline earth metals

They are malleable and ductile metals. The atoms of the elements in this group have an s ² configuration, so they can give up two electrons and their oxidation state is +2. With the exception of beryllium, they are oxidizable on exposure to air.

Post-transitional metals

They are metals of the so-called p block, located between the transition metals and the metalloids in the periodic table.

The elements of group 3 have the oxidation states +1 and +3 as the most common, although aluminum only has the oxidation state +3. Also part of the post-transitional metals are some located in groups 14 and 15.

Transition metals d

They form a group that are found between the base-forming elements and the acid-forming elements. The d and f atomic orbitals are incomplete and filling. Although the term transition metals refers to transition metals d.

Transition metals have more than one oxidation state. They have higher melting and boiling points than other groups of metals. The transition metals is a very heterogeneous group of metals that includes, among others, iron, chromium, silver, etc.

Rare earths

Rare earth ore

This group of metals is made up of the elements scandium and yttrium and the elements of the series of lanthanides and actinides. The term 'rare earths' refers to the fact that they are not found in nature in pure states and are attackable by acids.

Applications

Alkali metals

Lithium is used as a heat transfer medium in some nuclear reactors. It is used in some dry batteries and light accumulators. Lithium chloride and lithium bromide are hygroscopic compounds used in industrial drying and air conditioning processes.

Sodium is used in metallurgy of metals, such as titanium and zirconium. It is used in public lighting in sodium arc lamps. Sodium chloride (NaCl) is used as a food flavoring and for the preservation of meat.

Alkaline earth metals

Magnesium was used in photography as flash light and in fireworks. Barium is a component of alloys that are used in spark plugs because of the ease of the element to emit electrons. Barium salts are used to limit x-ray damage to plates in the gastrointestinal tract.

Calcium is used to remove dissolved impurities in molten metals and in the removal of waste gases in vacuum tubes. It is part of plaster, a material used in construction and in the treatment of bone fractures.

Post-transitional metals

Aluminum because it is a lightweight metal is used in the construction of aircraft and ships. It is also used in the production of numerous kitchen utensils. It is used as a raw material in the manufacture of deodorants that limit sweating.

Gallium is used in high temperature transistors and thermometers. The ⁶⁷ Ga isotope is used in medicine to treat some melanomas. Lead is used in the construction of batteries and in protection against ionizing radiation.

Transitional metals

Copper is used in water supply pipes, refrigerators, and air conditioning systems. It is also used as part of the heat dissipation mechanism of computers. It is used in the conduction of electric current, in electromagnets and in the coloring of glasses.

Nickel is used to make stainless steel, as well as for guitar strings and rechargeable batteries. It is also used in electroplating in the protection of metals. It is used in alloys found in vehicle parts, such as valves, bearings, and brakes.

Nickel has long been used in the making of coins.

Zinc is used to protect metals against corrosion, in the production of brass. Zinc oxide and zinc sulfate are used in the manufacture of sheets used in roofs, gutters and downspouts.

Chromium is used to protect metals against corrosion and gives them shine. It is used as a catalyst in the synthesis reaction of ammonia (NH ₃). Chromium oxide is used to protect wood.

Rare earths

Scandium is used in alloys with aluminum for aerospace components. It is an additive in mercury vapor lamps.

Lanthanum is used in alkali resistant, high refractive index glasses. In addition, it is used in the manufacture of camera lenses and as a catalytic cracking catalyst for oil refineries.

Cerium is used as a chemical oxidizing agent. Additionally, it is used to supply a yellow coloration in glass and ceramics, as well as a catalyst for self-cleaning ovens.

Examples of metallic elements

Alkaline

Sodium (Na), potassium (K), cesium (Cs), lithium (Li) and rubidium (Ru).

Alkaline-earthy

Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra).

Post-transitional

Aluminum (Al), gallium (Ga), Indium (In), thallium (Tl), tin (Sn) and lead (Pb).

Transitional

Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Zirconium (Zr), niobium (Nb), molybdenum (Mo), palladium (Pd), silver (Ag), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), Platinum (Pt), Gold (Au) and Mercury (Hg).

Rare earths

Scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

References

1. Whitten, Davis, Peck & Stanley. (2008). Chemistry (8th ed.). CENGAGE Learning.
2. Shiver & Atkins. (2008). Inorganic chemistry. (Fourth edition). Mc Graw Hill.
3. Helmenstine, Anne Marie, Ph.D. (October 05, 2019). Metals Versus Nonmetals. Recovered from: thoughtco.com
4. Metals And Their Properties- Physical and Chemical.. Recovered from: csun.edu
5. Jonathan Maes. (2019). 18 Different Types of Metal (Facts and Uses). Recovered from: makeitfrommetal.com