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What is a chemical element?

Chemical elements

The chemical elements or pure substances are the subject of what is known today. They are characterized by being made up of atoms of the same class and remain unchanged before the application of chemical forces. They are organized according to their properties in the so-called periodic table of the elements.

What is a chemical element?

The chemical element, also called an element , is a basic substance that makes up matter. It is indivisible through chemical reaction. It is composed of atoms of the same type, with particular physical characteristics. Each atom of the element is made up of the same number of protons , but not all of them are identical. There can be two or more atoms with different characteristics, determined by the number of neutrons. If the sum of their protons and neutrons, which indicates the mass number, is different, they are called isotope atoms.

Until 2020, 118 elements have been identified , 90 of them found naturally, forming simple substances or some chemical compound. The rest are the product of the acceleration of particles through electromagnetic fields or atomic, artificial and unstable reactions.

The number of protons in each atom of the element determines what is known as the atomic number. Characteristic that gives rise to it within the periodic table of the elements. In the table or matrix, substances are further ranked by electron configuration and chemical properties.

  • Characteristics of chemical elements
  • Source
  • History
  • Classification
  • Periodic properties
  • Names of chemical elements
  • Most important chemical elements for humans
  • Chemical elements toxic to humans
  • Commercial use of chemical elements
  • How are elements different from chemical compounds?

Characteristics of chemical elements

Chemical elements are made up of a class of atoms, whose nuclei contain the same number of protons .

They are mostly found in nature , only a small part of the chemical elements is obtained artificially. The latter last less than a second and are inconsistent.

Its nature remains unchanged in the face of chemical changes or thermodynamic processes.

They are found in different states at room temperature: gas, plasma, liquid or solid, depending on the element.

Elements of the same classification in the periodic table show similar chemical responses. Behavior determined by the structure of the nucleus and electronic configuration .

Source

Chemical elements have astronomical origin. At least the first part of them occurred during the primordial nucleosynthesis or nucleosynthesis of the Big Bang. It is assumed that when the early nucleus of the universe exploded, it evenly distributed matter and radiation in space. When this matter cooled, it created the first particles, called quarks, which when interacting with each other formed protons and neutrons.

The gravitational, magnetic and nuclear forces were already acting on what was created, like a kind of nuclear fusion reactor. Electrons stabilized and electromagnetic photons formed. Protons and neutrons formed nuclei of Deuterium (proton + neutron) and Helium (2 protons + 2 neutrons) , whose symbols are 2H and He, respectively. Deuterium is a stable isotope of Hydrogen (H).

It is believed that after the first 8 minutes of the Big Bang, one ¼ of the Universe was composed of He and ¾ of Hydrogen. Also less than a tenth of Deuterium and Lithium (Li) nuclei. Hence the abundance of these first elements in the universe.

Over time the temperature decreased, the first atoms formed and interacted with each other without being affected by radiation. The interaction added different atoms that formed the nuclei of stars . The nuclear reactions of the atoms contained in the astronomical bodies give rise to the chemical elements.

The synthesis of the elements depends on the temperature in the center of the star’s core. The H is transformed into He and the result is heavier elements and these in turn interact creating others of greater weight. One of the most stable heavy elements is iron (Fe).

The origin of the elements on earth is related to the forces that have acted on it. Accepting that the earth was an extremely hot body, which when expanding cooled and generated the different layers. This from a solid core formed by Fe and Nickel (Ni), a layer of magma and the outer crust.

History

There is no exact record of the dates of discovery of each of the chemical elements. If a list of these, in chronological order, according to the date on which they were mentioned for the first time in articles or reports.

Copper tops the list, its existence dates back to 9000 BC Although the oldest physical evidence dates back to 6000 BC, some copper beads found in Anatolia, Asia.

They are followed by gold, lead, silver and iron, whose samples are located between 6000 and 3750 BC, mostly in Anatolia and Egypt. Archaeologists point out that gold was perhaps the first metal used by humans.

Of carbon, tin, sulfur, mercury, zinc, arsenic, antimony and bismuth, also discovered and used in ancient times, there are not very precise data. Some of them, such as charcoal, were used by the Sumerians and Egyptians to obtain copper. And they were not recorded as pure elements until many centuries later.

Of the chemical elements identified from the year 1669, there are names of their researchers and interesting notes. The biologist Antoine Laurent de Lavoisier, father of modern chemistry, published the first list of elements in 1789 . Describe 23 in total and exclude all metals except mercury.

In 1869, the chemist Dmitri Ivanávich Mendeleev organized the 63 elements known in his time in the so-called periodic table of the elements . The table presents these substances according to their atomic number, electronic configuration, and chemical properties. Mendeleev then noticed the existence of other elements, not yet described.

The last chemical element discovered is oganeson, admitted as such in 2006, after the publication of its synthesis by Russian scientists.

Classification

Chemical elements are classified into three groups: metals, non-metals, and metalloids:

The metals are the most predominant in nature, they are characterized by their malleability and brightness. They contain between one and three electrons in their outermost shell, which give them easy conductivity. They are conductors of electricity and heat. This group is made up of gold, silver, copper, aluminum, iron, lead, nickel, sodium, potassium and zinc, among others.

The nonmetals comprise a smaller group differ from metals to present low specific weight and high capacity ionization. They contain between four and seven electrons in their last orbit. They are reduced by gaining electrons, they tend to do so to form negative ions. Two or more atoms make up its molecules. Nonmetals include oxygen, nitrogen, hydrogen, and carbon.

Some nonmetal elements have different atomic or molecular structures. This property is known as allotropy , they can manifest in different forms, each with particular physical and chemical characteristics.

Among the non-metals there are also noble gases , chemical elements with 8 electrons in their last valence shell. They have an inert nature, they do not react to other elements. Noble gases are neon, argon, radon and even helium, which exceptionally only has two electrons in its last shell.

The metalloids or semimetals , present physical and chemical characteristics as typical of the metal elements as of the nonmetals. They have four electrons in their outer shell, which allow them to conduct electricity or heat only in one direction. They are used to make semiconductor materials. Boron, arsenic, silicon and antimony, among others, are metalloids.

Periodic properties

The distribution of the elements in the periodic table obeys their physical-chemical properties, it is given by groups and periods. Among the properties or characteristics of chemical elements are:

  • The atomic number : Total number of protons that each atom of the element contains.
  • Electronegativity : Ability to attract electrons. This value is not calculated, but typified on a scale from 0.7 to 4.0, from higher to lower electronegativity, made by the chemist Linus Pauling. It is known as the Pauling scale.
  • Electropositivity : Ability to lose electrons. Metal elements are the most prone to electropositivity.
  • Atomic radius : The probable distance between the nucleus of the atom and the electrons that make up its last shell.
  • Electroaffinity : Or electronic affinity, it is the energy released when the neutral atom attracts an electron to form a negative ion.
  • Ionization energy : Potential necessary to separate an electron – in its essential state – from a neutral atom.

There are four other properties, less studied, perhaps because they are considered aperiodic:

  • Atomic density : It is the relationship between the mass of an atom and the volume, it depends on the temperature and the state in which the element is present, generally solid.
  • Atomic volume : It is calculated in the solid state, therefore it is variable.
  • Melting temperature: Point necessary for the element to change from a solid to a liquid state.
  • Boiling Point : Temperature necessary for an element in a liquid state to transform into vapor.

Names of chemical elements

The names of the chemical elements have various origins. Some have been named after a researcher, Mendelevius recalls Dmitri Ivanovich Mendeleev . Others, depending on the region or country where they were sighted, Teneso was discovered in Tennessee, United States of America.

Some Greek words have also been used, such as Hydrogen which means water engender. Latin words, such is the case of fluere or fluorine; and English words, such as pot ashes which means ashes and identifies potassium .

In any case, these are common names , which must be written in lowercase if they are found in the middle of the text. Plus its symbols will always be represented by the first letter in uppercase and a second in lowercase.

Listing and symbols

  1. Hydrogen (H)
  2. Helium (He)
  3. Lithium (Li)
  4. Beryllium (Be)
  5. Boron (B)
  6. Carbon (C)
  7. Nitrogen (N)
  8. Oxygen (O)
  9. Fluorine (F)
  10. Neon (Ne)
  11. Sodium (Na)
  12. Magnesium (Mg)
  13. Aluminum (Al)
  14. Silicon (Si)
  15. Phosphorus (P)
  16. Sulfur (S)
  17. Chlorine (Cl)
  18. Argon (Ar)
  19. Potassium (K)
  20. Calcium (Ca)
  21. Scandium (Sc)
  22. Titanium (Ti)
  23. Vanadium (V)
  24. Chromium (Cr)
  25. Manganese (Mn)
  26. Iron (Fe)
  27. Colbato (Co)
  28. Nickel (Ni)
  29. Copper (Cu)
  30. Zinc (Zn)
  31. Gallium (Ga)
  32. Germanium (Ge)
  33. Arsenic (As)
  34. Selenium (Se)
  35. Bromine (Br)
  36. Krypton (Kr)
  37. Rubidium (Rb)
  38. Strontium (Sr)
  39. Yttrium (Y)
  40. Zirconium (Zr)
  41. Niobium (Nb
  42. Molybdenum (Mo)
  43. Technetium (Tc)
  44. Ruthenium (Ru)
  45. Rhodium (Rh)
  46. Palladium (Pd)
  47. Silver (Ag)
  48. Cadmium (Cd)
  49. Indian (In)
  50. Tin (Sn)
  51. Antimony (Sb)
  52. Tellurium (Te)
  53. Iodine (I)
  54. Xenon (Xe)
  55. Cesium (Cs)
  56. Barium (Ba)
  57. Lanthanum (The)
  58. Cerium (Ce)
  59. Praseodymium (Pr)
  60. Neodymium (Nd)
  61. Promethium (Pm)
  62. Samarium (Sm)
  63. Europium (Eu)
  64. Gadolinium (Gd)
  65. Terbium (Tb)
  66. Dysprosium (Dy)
  67. Holmium (Ho)
  68. Erbium (Er)
  69. Thulium (Tm)
  70. Ytterbium (Yb)
  71. Lutetium (Lu)
  72. Hafnium (Hf)
  73. Tantalum (Ta)
  74. Tungsten (W)
  75. Rhenium (Re)
  76. Osmium (Os)
  77. Iridium (Go)
  78. Platinum (Pt)
  79. Gold (Au)
  80. Mercury (Hg)
  81. Thallium (Tl)
  82. Lead (Pb)
  83. Bismuth (Bi)
  84. Polonium (Po)
  85. Astato (At)
  86. Radon (Rn)
  87. Francio (Fr)
  88. Radius (Ra)
  89. Actinium (Ac)
  90. Thorium (Th)
  91. Protactinium (Pa)
  92. Uranium (U)
  93. Neptunium (Np)
  94. Plutonium (Pu)
  95. Americio (Am)
  96. Curium (Cm)
  97. Berkelium (Bk)
  98. Californium (Cf)
  99. Einsteinium (Es)
  100. Fermium (Fm)
  101. Mendelevium (Md)
  102. Nobelio (No)
  103. Laurencio (Lr)
  104. Rutherfordio (Rf)
  105. Dubnium (Db)
  106. Seaborgio (Sg)
  107. Bohrio (Bh)
  108. Hassio (Hs)
  109. Meitnerium (Nt)
  110. Darmstatio (Ds)
  111. Roentgenio (Rg)
  112. Copernicium (Cn)
  113. Nihonium (Nh)
  114. Flerovio (Fl)
  115. Moscovio (Mc)
  116. Livermorio (Lv)
  117. Tenese (Ts)
  118. Oganeson (Og)

Most important chemical elements for humans

The human body is made up of more than half of the known chemical elements. Four of them are fundamental: oxygen, carbon, hydrogen and nitrogen , they constitute 96% of the organism at a chemical level. Calcium and phosphorus are added in order of importance. Also potassium, sulfur, sodium, chlorine, magnesium and iron. While other elements such as silicon, zinc or iodine, are presented in minimal proportions.

Chemical elements toxic to humans

The elements that are toxic or harmful to humans are arsenic, lead, aluminum, cadmium and mercury. They access the body through food, water, air (after the emission of toxins) and even through articles of daily use. Its presence – even in low proportions – produces unfavorable changes in the genetics and metabolism of living beings.

Commercial use of chemical elements

The pure chemical elements are used in the elaboration of infinity of substances or compounds of great benefit for the industry. They are used as a base material for construction. In the manufacture of household cleaning and maintenance products. Also in field work, for the improvement of agriculture, as part of herbicides, insecticides, fertilizers and phytoregulators.

How are elements different from chemical compounds?

Elements must be distinguished from simple substances and chemical compounds. The former are made up of molecules (bonding of atoms with a defined and stable configuration) of a single chemical element. While compounds, they result from the combination of two or more elements of the periodic table. Millions of compounds can be made from the 118 known elements.

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