Nonmetals: History, Properties, Groups, Uses

The nonmetals are a group of elements that are located on the right side of the periodic table, except for the hydrogen is located in group 1 (IA), with the alkali metals. If you want to know what they are, you have to look at the upper right corner of the p block.

Nonmetal atoms are relatively small and their outer electronic shell has a high number of electrons. Non-metallic elements include solids, liquids and gases; Although most of them are in a gaseous state , several of them enriching the atmosphere .

A good part of nonmetals are present in all living beings in the form of compounds and macromolecules. For example: carbon, oxygen, and hydrogen are present in all proteins, lipids, carbohydrates, and nucleic acids.

Phosphorus is present in all nucleic acids and in some carbohydrates and lipids. Sulfur is found in many proteins. Nitrogen is part of all nucleic acids and proteins.

On the other hand, underground, methane gases and crude oil are composed almost entirely of non-metallic elements. In fact, hydrocarbons (carbon and hydrogen) give an idea of ​​how abundant nonmetals are despite their lower number of elements in the periodic table.

History

Since ancient times (3750 BC) the Egyptians used coal to reduce the copper present in their minerals, such as corvellite and malachite.

In 1669, Hennin Brand succeeded in isolating phosphorus from collected urine. Henry Cavendish (1776) succeeded in identifying hydrogen, although several researchers, including Robert Boyle (1670), produced hydrogen by reacting a strong acid with a metal.

Carl Scheele produced oxygen by heating oxide of mercury with nitrates (1771). Curtois succeeded in isolating the iodine while trying to prepare saltpeter from seaweed (1811). Balard and Gmelin isolated bromine (1825).

In 1868, Janssen and Lockger independently discovered helium by observing a yellow line in the study of the spectrum of sunlight that did not belong to another element. Moissan succeeded in isolating fluorine (1886).

In 1894 Lord Rayleigh and Ramsey discovered argon by studying the properties of nitrogen. Ramsay and Travers (1898) isolated krypton, neon, and xenon from liquid argon by cryogenic distillation from air.

Physical and chemical properties

Physical

Some of the physical properties of nonmetals are:

-They have low electrical conductance, except for carbon in the form of graphite, which is a good conductor of electricity.

-They can appear under the physical appearance of solids, liquids or gases.

-They have low thermal conductance, except for carbon in the form of diamond, which does not behave as a thermal insulator.

-They have little luster, unlike the metallic luster of metals.

-Non-metallic solids are brittle, so they are not ductile or malleable.

-They have low melting and boiling points.

-They can have different crystalline structures. Thus phosphorus, oxygen and fluorine have a cubic crystalline structure; hydrogen, carbon and nitrogen, hexagonal; and sulfur, chlorine, bromine and iodine, orthorhombic.

Chemistry

Nonmetals are characterized by having a high ionization energy and a high electronegativity value. Fluorine, for example, has the highest electronegativity (3.98), being the most reactive element of the nonmetals.

But surprisingly, the noble gases helium (5.5) and neon (4.84) ​​have the highest electronegativity. However, they are chemically inert because the outer electronic shells are full.

Nonmetals form ionic compounds with metals, and covalent with nonmetals.

Non-metallic elements are found forming diatomic molecules, linked by covalent bonds. Meanwhile, the atoms of noble gases are in the form of atomic units.

They form acid oxides that react with water to create acids.

Nonmetal groups and elements

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Group 1

It is made up of hydrogen, a colorless and odorless gas, diatomic. Oxidation state +1. It has a lower density than air. In the solid state it has a hexagonal crystalline structure. Hydrogen is not very reactive.

Group 14

Carbon is the only non-metal in this group. Carbon in the form of graphite is a lustrous solid, with a hexagonal crystalline structure. It has a high electrical conductivity. Its most common oxidation states are +2 and +4.

Group 15

Nitrogen

Colorless and odorless gas. It is a slightly reactive element and slightly more dense than air. Most common oxidation states: -3 and +5. It forms diatomic molecules, N 2 .

Match

Solid, its color can be white, yellow or black. Little reactive. Orthorhombic crystal structure. Electronegativity 2.1. Most common oxidation states: -3 and +5.

Group 16

Oxygen

Colorless or pale blue gas, odorless. Generally non-reactive. Cubic crystal structure. It is an insulator and a strong oxidizing agent. Electronegativity 3.5. Oxidation state -2

Sulfur

Bright yellow, brittle, moderately reactive solid. Orthorhombic crystal structure. Forms covalent bonds. Electronegativity 2.5. Most common oxidation states: -2, +2, +4, and +6.

Selenium

Gray or reddish to black solid. Gray selenium exhibits light sensitive electrical conductivity. It is a soft and brittle solid. Electronegativity 2.4. Oxidation states: -2, +2, +4 and +6.

Group 17

Fluorine

It is a pale yellow gas, very toxic. It is a very reactive element. It occurs as diatomic molecules, F 2 . In solid state it crystallizes in cubic form. Electronegativity 3.98. Oxidation states -1.

Chlorine

It is a green-yellow gas. It presents diatomic molecules, Cl 2 . It is very reactive. In solid state the crystalline structure is orthorhombic. Electronegativity 3.0. Oxidation states: – 1, +1, +3, +5, +7.

Bromine

It is a red-brown liquid. Electronegativity 2.8. Oxidation states -1, +1, +3, +5 and +7.

Iodine

It is a solid of black color that when sublimated emits a violet vapor. Orthorhombic crystal structure. Metal iodides are ionic. Electronegativity 2.5. Oxidation states: -1, +1, +3, +5, and +7.

Astatus

It is a solid black. Cubic crystal structure centered on the face. Electronegativity 2.2. It is a weak oxidizing agent.

Group 18

Helium

It has a high thermal conductivity. Electronegativity 5.5. It is chemically inert and non-flammable. Low density and high fluidity.

Neon

High cooling capacity in liquid state . Electronegativity 4.84. It is the least reactive of the noble gases.

Argon

It is denser than air. Chemically inert. Electronegativity 3.2.

Krypton

Electronegativity 2.94. It can react with fluorine to form krypton difluoride (KrF 2 ).

Xenon

It crosses the blood-brain barrier. It responds to electric current by producing light. Electronegativity 2.2. Forms complexes with fluorine, gold, and oxygen.

Radon

It is a radioactive element. Electronegativity 2.06. It forms compounds with fluorine (RnF 2 ) and with oxygen (RnO 3 ).

Applications

Hydrogen

It is used in rocket propulsion and as a fuel in car engines that use hydrogen. It is used in the synthesis of ammonia (NH 3 ) and in the hydrogenation of fats.

Carbon

Graphite is used to make pencils and high-strength fibers that are used to make sporting goods. Diamond is used as a high-value gem and in drill holes as an abrasive. Carbon dioxide is used in the production of carbonated beverages.

Nitrogen

It is used in the production of ammonia, nitric acid and urea. Nitrogen is an essential element for plants and is used in the manufacture of fertilizers.

Match

White phosphorus is used as a rodenticide, insecticide and in the fireworks industry. Red phosphorus is used in the making of matches. Its compounds are also used in making fertilizers.

Oxygen

Oxygen is used in the manufacture of steel, plastics and textiles. It is also used in rocket propellants, oxygen therapy, and breathing assistance on aircraft, submarines, and spaceflight.

Sulfur

It is used as a raw material for the production of sulfuric acid, gunpowder and in the vulcanization of rubbers. Sulfites are used to bleach paper and in fungicide.

Selenium

It is used to impart a scarlet red tint to glass. It is also used to neutralize the greenish tinge produced by contamination of the glass with iron compounds. It is used in photoelectric cells with application in doors and elevators.

Fluorine

It is added to toothpastes to prevent cavities. Hydrogen fluoride is used as a raw material for Teflon. Monatomic fluorine is used in the manufacture of semiconductors.

Chlorine

It is used in extractive metallurgy and in the chlorination of hydrocarbons for the manufacture of various products such as PVC. Chlorine is used in wood pulp and textile bleaches. It is also used as a water disinfectant.

Bromine

It is used in the preparation of silver bromide for light-sensitive lenses and in photographic film. It is also used in the manufacture of the sedative sodium bromide and dibromethane, an antiknock component in gasoline.

Iodine

Potassium iodide (KI) is added to prevent thyroid goiter. The tincture of iodine is used as an antiseptic and germicide. Iodine is part of the thyroid hormones.

Helium

It is used in the filling of hot air balloons and mixed with oxygen for deep water respiration. It is used for welding in an inert atmosphere, and also helps to maintain very low temperatures in research.

Neon

In glass tubes that are illuminated by the action of electricity (red neon lights).

Argon

It is used to create an atmosphere for welding and when filling incandescent bulbs.

Xenon

A mixture of xenon and krypton is used in the production of high intensity flashes in short photographic exposures.

Radon

It is used in the treatment of cancerous tumors by radiation therapy.

References

  1. Whitten, Davis, Peck & Stanley. (2008). Chemistry . (8th ed.). CENGAGE Learning.
  2. Shiver & Atkins. (2008). Inorganic Chemistry . (Fourth edition). Mc Graw Hill.
  3. Mathews, CK, van Holde, KE and Ahern, KG (2002). Biochemistry . Third edition. Edit. Pearson-Addison Wesley
  4. Helmenstine, Anne Marie, Ph.D. (October 06, 2019). What Are the Properties of Nonmetals? Recovered from: thoughtco.com
  5. Wikipedia. (2019). Nonmetal. Recovered from: en.wikipedia.org
  6. The Editors of Encyclopaedia Britannica. (April 5, 2016). Nonmetal. Encyclopædia Britannica. Recovered from: britannica.com
  7. José M. Gavira Vallejo. (January 27, 2016). What are the polygenic elements? And the icosagens, the crystallógens, the chalcogens …? Recovered from: triplenlace.com

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