periodic table



We explain what the periodic table is and what its history is. In addition, how it is organized and what are the different groups it contains.

The elements are represented with their respective chemical symbols.

What is the Periodic Table?

The Periodic Table of the Elements is a record of all the chemical elements known for the humanity. The elements are arranged in table form according to their atomic number (number of protons), its electronic configuration and its chemical properties.

In this table the elements are organized in rows and columns that show a certain periodicity: the elements that belong to the same column have similar properties. In principle, the entire matter known from universe It is composed of various combinations of the 118 elements, recorded in the Periodic Table.

Symbols, called chemical symbols, have been established to represent each element in the Periodic Table, which are also identified according to their aggregation states (solid, liquid or gas) to a temperature 0 ° C and a Pressure of 1atm.

The Periodic Table is a fundamental tool for the chemistry, the biology and others natural Sciences, which is updated over the years, as we learn more about the properties of matter and the relationships between the elements.

History of the periodic table

The first version of the Periodic Table was published in 1869 by the Russian chemistry professor Dmitri Mendeleev, and contained 63 of the 118 elements known today in the nature and it was organized on the basis of its chemical properties. On the other hand, the German chemistry professor Julius Lothar Meyer published an expanded version but based on the physical properties of the atoms. Both scholars organized the elements in rows, having the anticipation of leaving blank spaces where they intuited that there would be elements yet to be discovered.

In 1871 Mendeleev published another version of the Periodic Table that grouped the elements according to their common properties in columns numbered from I to VIII according to the state of oxidation of the element.

Finally, in 1923 the American chemist Horace Groves Deming published a periodic table with 18 identified columns that constitutes the version currently used.

How is the periodic table organized?

The current periodic table is structured in seven (horizontal) rows named periods and in 18 (vertical) columns called groups or families. Chemical elements are arranged in increasing order of their atomic numbers, that is, the atomic number increases from left to right in the period and from top to bottom in the group.

The eighteen known groups are:

  • Group 1 (IA). The metals alkaline: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr). Also in this group is hydrogen (H), which is a gas.
  • Group 2 (IIA). The alkaline earth metals: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra).
  • Group 3 (IIIB). The Scandium (Sc) family, which includes Yttrium (Y) and rare earths: Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yt), lutetium (Lu). Actinides are also included: actinium (Ac), thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk ), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No) and lawrencium (Lr).
  • Group 4 (IVB). The titanium (Ti) family, which includes zirconium (Zr), hafnium (Hf) and rutherfordium (Rf), the latter synthetic and radioactive.
  • Group 5 (VB). The vanadium (V) family: niobium (Nb), tantalum (Ta) and dubnium (Db), the latter is synthetic.
  • Group 6 (VIB). The chromium (Cr) family: molybdenum (Mb), tungsten (W) and seaborgium (Sg), the latter is synthetic.
  • Group 7 (VIIB). The manganese (Mn) family: rhenium (Re), technetium (Tc) and bohrio (Bh), the latter two are synthetic.
  • Group 8 (VIIIB). The iron (Fe) family: ruthenium (Ru), osmium (Os) and hassium (Hs), the latter synthetic.
  • Group 9 (VIIIB). The cobalt family (Co): rhodium (Rh), iridium (Ir) and the synthetic meitneiro (Mt).
  • Group 10 (VIIIB). The family of nickel (Ni): palladium (Pd), platinum (Pt) and the synthetic darmstadtium (Ds).
  • Group 11 (IB). The family of copper (Cu): silver (Ag), gold (Au) and the synthetic roentgenium (Rg).
  • Group 12 (IIB). The zinc (Zn) family: cadmium (Cd), mercury (Hg) and the synthetic copernicium (Cn).
  • Group 13 (IIIA). The earths: boron (Br), aluminum (Al), gallium (Ga), indium (In), thallium (Tl) and the synthetic nihonium (Nh).
  • Group 14 (VAT). The carbonids: carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) and the synthetic flevorio (Fl).
  • Group 15 (VA). The nitrogenoids: nitrogen (N), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi) and the synthetic moscovio (Mc).
  • Group 16 (VIA). Chalcogens or amphigens: oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po) and the synthetic livermorio (Lv).
  • Group 17 (VIIA). Halogens: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astate (At) and the synthetic tenese (Ts).
  • Group 18 (VIIIA). The Noble gasesHelium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and the synthetic oganeson (Og).
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