One calls

chemical element of pure materials, which continue to themselves divide also chemically not, chemical elements.

Greek coin with Demokrit and atomic representation

you exclusively consist of atoms with same number of protons in the core (nuclear charge number) and step intoUniverse with a certain element frequency on (Kosmochemie). The chemical elements count like the connections to the pure materials. Pure materials are physically not further separable and stand thus contrary to the material mixtures.

In former times the definition was thisTerm more intuitively, but more imprecisely:Robert Boyle defined a chemical element as a pure material, which can be not further divided with chemical methods. This definition has the disadvantage that one can be safe never, whether one the chemical methods completelyexhausted. It would be z. B. in the laboratory successfully, water into its components to divide then one would not have had to arrange it as element.

The today's element term, which for the materials an organization according to their components, which makes atoms,is more abstractly, precise but however. Its practical meaning lies in the fact that it summarizes atoms with same chemical behavior (the behavior with chemical reactions). The physical behavior of atoms the same element can be quite different thereby, z. B.can the atoms of an element in the mass differ (isotopes) hold back and with nuclear reactions differently.

According to the nuclear charge number (ordinal number) and the Elektronenkonfiguration of its atoms one arranges the elements in the periodic system of the elements (PSE) into Groups and periods on. This system was justified by the Russian scholar Dmitri Iwanowitsch Mendeleyev at the same time with the German Lothar Meyer 1869.

The abbreviation or abbreviation becomes from usually latin name of the element (O von Oxygenium, Hg von Hydrargyrum etc.)derived.

Chemical elements over proof reactions of analytic chemistry are identified - its emergence and distribution in the universe describe the Kosmochemie.

Table of contents

nuclear charge number and mass

the explanations for it that the mass number does not correspond exactly to the multiples of the mass of the hydrogen atom, are:

  • Protons and neutrons, which form the principal part of the mass,are however not exactly, equivalent heavy nearly.
  • Natural elements consist of a mixture of atoms with different neutron number. An atomic kind outweighs usually by far, these certainly then the mass number (exception chlorine Cl with the 35,5-fachen mass)
  • the natural mixing ratio is with an element usually directly (exception is lead, which shows different average atomic masses, if one wins it from different stores)
  • when very precise measurements the binding energy shows up as mass defect, so that the core mass is always minimum smaller thanthe sum of the masses of the protons and neutrons.

pure and mixing elements

the core of the hydrogen nearly always consists of only one proton. Hydrogen with a proton and a neutron in the core (deuterium) step in naturalHydrogen with a portion of 0,015% up.

The helium core consists of two protons and two neutrons. In addition, exist helium atoms, which contain two protons, but only one neutron. These step in natural helium however only with a portionof 0,000137% up.

Chlorine (17 protons) consists of a mixture of atoms with 18 neutrons (75.8%) and 20 neutrons (24.2%).

Chemical elements, which consist only of an atomic kind, are called pure elements, if them against it from two orthey exist, are called more atomic kinds mixing elements. One calls atoms of the same element with different neutron number isotopes.

chemical compounds

chemical elements can, except for few exceptions, which noble gases, chemical compounds to be received. Several are thatelementary atoms to molecules or ion crystals united.

Natural or artificial pure materials are either elements or connections.

Elements can be received a connection with other elements or also with itself: With many gases such as chlorine Cl or Fluor F are connectedtwo atoms of the same element among themselves to a molecule, thus Cl 2 and/or. F 2. Usual water (sum formula: H 2 O) is however a connection from the elements hydrogen H (2 atoms per molecule) and oxygen (1 atomper molecule).

Metals such as iron Fe or copper cu are always against it elements.

In principle give it to four kinds of chemical compounds between the atoms of the elements:

  • Molecular connections develop from nonmetal and nonmetal - they are nonconductors with mostly relativelow boiling point (diamond-well-behaved or plastic-well-behaved connections with giant molecules excluded). Examples of molecular connections are beside water also methane gas, sugar) etc.
  • Ioni connections develop from metal (cation) and nonmetal (anion). They are salt-like: inflexibly, of high melting point and electrically conductive onlyin melt or solution. Examples of ionic compounds are iron ii-oxide (the rust similarly) and common salt (sodium chloride).
  • Metallic connections develop made of metal and metal - they are electrically conductive, well ductile, shining and good heat leaders. Examples of such alloys are bronze and Brass).
  • Connections of higher order (complexes) develop with a complex education reaction mostly from non-ferrous metal cation and molecules with free pairs of electrons (ligands). They are often remarkably colored; Examples: The red blood coloring material hemoglobin from iron ii-ions and protein molecules and the low-blue Kupfertetrammin complex from copper ii-ions andAmmonia).

the emergence of elements

with the Big Bang the light elements hydrogen already developed (approx. 75%) and helium (approx. 25%), together with small quantities lithium and beryllium.

"Gürtelsterne" und Orionnebel im Wintersternbild Orion (Foto von M.Wächter,1983): Entstehen hier aus den im Weltall verstreuten chemischen Elementen neue Sterne?
“Belt stars” and Orionnebel in the winter constellation Orion (photo of M.Wächter, 1983): Develophere from the chemical elements new stars scattered in the universe?

Heavier elements result in the universe from nuclear reactions in the stars (usually by nuclear fusion). At the beginning of the Kosmochemie therefore the hydrogen with an atomic weight of approx. stands. 1,0 (a proton).In Hauptreihen-Sternen, like also our sun, hydrogen merges into helium under high temperature (several million C°) and high pressure. (Atomic weight approx. 4,0) 4 hydrogen atom cores merge over several intermediate stages into a helium atomic nucleus. This is a little easier thanthe four protons together, which become mass difference as energy in the form of (gamma) radiation freely.

The fusion goes on this kind (atoms with smaller proton number and atomic weight to merge into higher under delivery of energy) in most stars up to carbon,in massive up to the iron further. The energy output becomes ever smaller thereby.Iron is the most closely packed atomic nucleus, with fusion reactions energy used up instead of is beyond that set free. Stars are dependent on power production from nuclear fusion, in order to stop their gravitational collapse, thereforecannot such reactions to considerable extent take place.

Elements more heavily than iron develop in stars at the end of their life span. Atomic nuclei catch neutrons and into elements of higher ordinal number are in such a way converted. This happens during the so-called s-process (with mass-poor stars)or during the r-process (with massive stars during supernew facts).

A star loses large quantities material (continuously by solar wind or explosively in supernew facts) of the end of its life span, thus the developed elements arrive back into the interstellar medium. Recent star systemscontained therefore it already from the outset also small quantities of heavier elements, e.g.Planets as in our solar system to form can.

list of chemical elements

Name chemical symbol Ordinal number atomic weight density with 20 degrees Celsius melting point boiling point discovery year discoverer
Actinium AC 89 227.0278 g/mol 10.07 kg/l 1047 °C 3197 °C 1899 Debierne
aluminum aluminium 13 26.981539 g/mol 2.70 kg/l 660.5 °C 2467 °C 1825 Oersted
americium at 95 243.0614 g/mol 13.67 kg/l 994 °C 2607 °C 1944 Seaborg
the antimony Self-service 51 121.75 g/mol 6.69 kg/l 630.7 °C 1750 °C prähistorisch unknown
argon acre 18 39.948 g/mol 1.66 g/l -189.4 °C -185.9 °C 1894 Ramsay and Rayleigh
arsenic As 33 74.92159 g/mol 5.72 kg/l 613 °C 613 (sublimated) °C approx. 1250 Albertus Magnus
astatine RK 85 209.9871 g/mol 302 °C 337 °C 1940 Corson and MacKenzie
barium Ba 56 137.327 g/mol 3.65 kg/l 725 °C 1640 °C 1808 Davy
berkelium UC 97 247.0703 g/mol 13.25 kg/l 986 °C 1949 Seaborg
beryllium 4 9.012182 g/mol 1.85 kg/l 1278 °C 2970 °C 1797 Vauquelin
lead Pb 82 207.2 g/mol 11.34 kg/l 327.5 °C 1740 °C prähistorisch unknown
Bohrium Bh 107 262.1229 g/mol 1976 Oganessian
boron B 5 10.811 g/mol 2,46 kg/l 2300 °C 2550 °C 1808 Davy and. Gay Lussac
bromine Br 35 79.904 g/mol 3.14 kg/l -7.3 °C 58.8 °C 1826 Balard
cadmium CD 48 112.411 g/mol 8.64 kg/l 321 °C 765 °C 1817 Stromeyer and Hermann
cesium Cs 55 132.90543 g/mol 1.90 kg/l 28.4 °C 690 °C 1860 Kirchhoff and Bunsen
calcium approx. 20 40.078 g/mol 1.54 kg/l 839 °C 1487 °C 1808 Davy
Californium Cf 98 251.0796 g/mol 15.1 kg/l 900 °C 1950 Seaborg
cerium Ce 58 140,115 g/mol 6.77 kg/l 798 °C 3257 °C 1803 of Hisinger and Berzelius
chlorine Cl 17 35.4527 g/mol 2.95 g/l -101 °C -34.6 °C 1774 cross-eyed
chrome CR 24 51.9961 g/mol 7.14 kg/l 1857 °C 2482 °C 1797 Vauquelin
curium Cm 96 247.0703 g/mol 13.51 kg/l 1340 °C 1944 Seaborg
Darmstadtium DS 110 ,269 g/mol 1994 society for heavy ion research
Dubnium railways 105 262.1138 g/mol 1967/70 Flerow or Ghiorso
dysprosium Dy 66 162.5 g/mol 8.56 kg/l 1409 °C 2335 °C 1886 Lecoq de Boisbaudran
einsteinium it 99 252.0829 g/mol 860 °C 1952 Seaborg
iron Fe 26 55.847 g/mol 7.87 kg/l 1535 °C 2750 °C prähistorisch unknown
erbium it 68 167.26 g/mol 9.05 kg/l 1522 °C 2510 °C 1842 MOS other
europium European Union 63 151.965 g/mol 5.25 kg/l 822 °C 1597 °C 1901 Demaçay
fermium of FM 100 257.0951 g/mol 1952 Seaborg
Fluor F 9 18.9984032 g/mol 1.58 g/l -219.6 °C -188,1 °C 1886 Moissan
francium Fr 87 223.0197 g/mol 27 °C 677 °C 1939 Perey
gadolinium Gd 64 157.25 g/mol 7.89 kg/l 1311 °C 3233 °C 1880 de Marignac
gallium Ga 31 69.723 g/mol 5.91 kg/l 29.8 °C 2403 °C 1875 Lecoq de Boiskaudran
germanium Ge 32 72.61 g/mol 5.32 kg/l 937.4 °C 2830 °C 1886 Winkler
gold outer one 79 196.96654 g/mol 19.32 kg/l 1064.4 °C 2940 °C prähistorisch unknown
hafnium Hf 72 178.49 g/mol 13.31 kg/l 2150 °C 5400 °C 1923 Coster and vón Hevesy
Hassium Hs 108 ,265 g/mol 1984 societyfor heavy ion research
helium He 2 4.002602 g/mol 0.17 g/l -272.2 °C -268.9 °C 1895 Ramsay and Cleve
holmium Ho 67 164.93032 g/mol 8.78 kg/l 1470 °C 2720 °C 1878 Soret
Indium in 49 114.82 g/mol 7.31 kg/l 156.2 °C 2080 °C 1863 realm and judge
iodine I 53 126.90447 g/mol 4.94 kg/l 113.5 °C 184.4 °C 1811 Courtois
iridium IR 77 192.22 g/mol 22.65 kg/l 2410 °C 4130 °C 1803 Tenant and other
potassium K 19 39.0983 g/mol 0,86 kg/l 63.7 °C 774 °C 1807 Davy
cobalt CO 27 58.9332 g/mol 8.89 kg/l 1495 °C 2870 °C 1735 Brandt
carbon C 6 12.011 g/mol 3.51 kg/l 3550 °C 4827 °C prähistorisch unknown
krypton Kr 36 83.8 g/mol 3,48 g/l -156.6 °C -152.3 °C 1898 Ramsay and Travers
copper cu 29 63.546 g/mol 8.92 kg/l 1083.5 °C 2595 °C prähistorisch unknown
lanthans La 57 138.9055 g/mol 6.16 kg/l 920 °C 3454 °C 1839 MOS other
lawrenciums Lr 103 260,1053 g/mol 1961 Ghiorso
lithium left 3 6.941 g/mol 0.53 kg/l 180.5 °C 1317 °C 1817 Arfvedson
lutetium Lu 71 174.967 g/mol 9.84 kg/l 1656 °C 3315 °C 1907 Urbain
magnesium mg 12 24.305 g/mol 1.74 kg/l 648.8 °C 1107 °C 1755 Black
manganese Mn 25 54.93805 g/mol 7.44 kg/l 1244 °C 2097 °C 1774 yawn
to Meitnerium Mt 109 ,266 g/mol 1982 society for heavy ion research
mendelevium MD 101 258.0986 g/mol 1955 Seaborg
molybdenum Mo 42 95.94 g/mol 10.28 kg/l 2617 °C 5560 °C 1778 cross-eyed
sodium well 11 22.989768 g/mol 0.97 kg/l 97.8 °C 892 °C 1807 Davy
neodymium lp 60 144.24 g/mol 7.00 kg/l 1010 °C 3127 °C 1895 of Welsbach
neon Ne 10 20.1797 g/mol 0.84 g/l -248,7 °C -246.1 °C 1898 Ramsay and. Travers
neptunium NP 93 237.0482 g/mol 20.48 kg/l 640 °C 3902 °C 1940 McMillan and Abelson
nickel never 28 58.69 g/mol 8.91 kg/l 1453 °C 2732 °C 1751 Cronstedt
niobium Nb 41 92,90638 g/mol 8.58 kg/l 2468 °C 4927 °C 1801 Hatchet
nobelium NO 102 259.1009 g/mol 1958 Seaborg
osmium OS 76 190.2 g/mol 22.61 kg/l 3045 °C 5027 °C 1803 Tenant
palladium Pd 46 106.42 g/mol 12.02 kg/l 1552 °C 3140 °C 1803 Wollaston
phosphorus P 15 30.973762 g/mol 1.82 kg/l 44 (P4) °C 280 (P4) °C 1669 Brandt
platinum Pt 78 195.08 g/mol 21.45 kg/l 1772 °C 3827 °C 1557 Scaliger
plutonium Pu 94 244.0642 g/mol 19.74 kg/l 641 °C 3327 °C 1940 Seaborg
polonium Po 84 208.9824 g/mol 9.20 kg/l 254 °C 962 °C 1898 Marie and Pierre curie
praseodymium Pr 59 140.90765 g/mol 6.48 kg/l 931 °C 3212 °C 1895 of Welsbach
promethium Pm 61 146,9151 g/mol 7.22 kg/l 1080 °C 2730 °C 1945 Marinsky and Glendenin
protactinium Pa 91 231.0359 g/mol 15.37 kg/l 1554 °C 4030 °C 1917 Soddy, Cranston and cock
mercury Hg 80 200.59 g/mol 13.55 kg/l -38.9 °C 356.6 °C prähistorisch unknown
radium RA 88 226.0254 g/mol 5.50 kg/l 700 °C 1140 °C 1898 Marie and Pierre curie
radon Rn 86 222.0176 g/mol 9.23 g/l -71 °C -61.8 °C 1900 thorn
rhenium RH 75 186.207 g/mol 21.03 kg/l 3180 °C 5627 °C 1925 Noddack, Tacke and mountain
rhodium RH 45 102.9055 g/mol 12.41 kg/l 1966 °C 3727 °C 1803 Wollaston
Roentgenium Rg 111 ,272 g/mol 1994 society for heavy ion research
rubidium Rb 37 85.4678 g/mol 1.53 kg/l 39 °C 688 °C 1861 Bunsen and Kirchhoff
ruthenium Ru 44 101.07 g/mol 12.45 kg/l 2310 °C 3900 °C 1844 Claus
Rutherfordium Rf 104 261.1087 g/mol 1964/69 Flerow or Ghiorso
samarium Sm 62 150.36 g/mol 7.54 kg/l 1072 °C 1778 °C 1879 Lecoq deBoisbaudran
oxygen O 8 15.9994 g/mol 1.33 g/l -218.4 °C -182.9 °C 1774 Priestley and cross-eyed
scandium sports club 21 44.95591 g/mol 2.99 kg/l 1539 °C 2832 °C 1879 Nilson
sulfur S 16 32.066 g/mol 2.06 kg/l 113 °C 444.7 °C prähistorisch unknown
Seaborgium Sg 106 263.1182 g/mol 1974 Oganessian
selenium SE 34 78.96 g/mol 4.82 kg/l 217 °C 685 °C 1817 Berzelius
silver AG 47 107.8682 g/mol 10.49 kg/l 961.9 °C 2212 °C prähistorisch unknown
silicon SI 14 28.0855 g/mol 2,33 kg/l 1410 °C 2355 °C 1824 Berzelius
nitrogen N 7 14.00674 g/mol 1.17 g/l -209.9 °C -195.8 °C 1772 Rutherford
strontium SR 38 87.62 g/mol 2.63 kg/l 769 °C 1384 °C 1790 Crawford
tantalum TA 73 180.9479 g/mol 16,68 kg/l 2996 °C 5425 °C 1802 Ekeberg
technetium Tc 43 98.9063 g/mol 11.49 kg/l 2172 °C 5030 °C 1937 Perrier and Segrè
tellurium of width unit 52 127.6 g/mol 6.25 kg/l 449.6 °C 990 °C 1782 of realm stone
terbium Tb 65 158,92534 g/mol 8.25 kg/l 1360 °C 3041 °C 1843 MOS other
thallium tl 81 204.3833 g/mol 11.85 kg/l 303.6 °C 1457 °C 1861 Crookes
thorium Th 90 232.0381 g/mol 11.72 kg/l 1750 °C 4787 °C 1829 Berzelius
thulium TM 69 168,93421 g/mol 9.32 kg/l 1545 °C 1727 °C 1879 Cleve
titanium Ti 22 47.88 g/mol 4.51 kg/l 1660 °C 3260 °C 1791 Gregor and Klaproth
Ununbium Uub 112 ,277 g/mol 1996 society for heavy ion research
Ununhexium Uuh 116
Ununoctium Uuo 118
Ununpentium Uup 115
Ununquadium Uuq 114
Ununseptium Uus 117
Ununtrium Uut 113
uranium U 92 238.0289 g/mol 18.97 kg/l 1132.4 °C 3818 °C 1789 Klaproth
vanadium V 23 50.9415 g/mol 6.09 kg/l 1890 °C 3380 °C 1801 del Rio
hydrogen H 1 1.00794 g/mol 0.084 g/l -259.1 °C -252.9 °C 1766 Cavendish
bismuth Bi 83 208.98037 g/mol 9.80 kg/l 271.4 °C 1560 °C 1540 Agricola
tungsten W of 74 183.85 g/mol 19.26 kg/l 3407 °C 5927 °C 1783 brothers de Elhuyar
Xenon Xe 54 131.29 g/mol 4.49 g/l -111.9 °C -107 °C 1898 Ramsay and Travers
ytterbium Yb 70 173.04 g/mol 6.97 kg/l 824 °C 1193 °C 1878 de Marignac
yttrium Y 39 88.90585 g/mol 4.47 kg/l 1523 °C 3337 °C 1794 Gadolin
zinc Zn 30 65.39 g/mol 7.14 kg/l 419.6 °C 907 °C prähistorisch unknown
tin SN 50 118.71 g/mol 7.29 kg/l 232 °C 2270 °C prähistorisch unknown
zirconium Zr 40 91.224 g/mol 6.51 kg/l 1852 °C 4377 °C 1789 Klaproth


literature

  • Lucien F. Cloudily: The chemical elements. An excursion by the periodic system. S. Hirzel publishing house, Stuttgart 2005, ISBN 3-7776-1356-8

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see also

 

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