Chemical element, our latest simulations http://www.edumedia-sciences.com/ eduMedia, RSS feeds en quentin.thiaucourt@edumedia-sciences.com http://www.edumedia-sciences.com/media/logo.jpg Logo http://www.edumedia-sciences.com/ <![CDATA[Mendeleev (Historical)]]>

In 1869 the Russian chemist D. I. Mendeleev discovered that pure chemical elements (containing a single kind of atom) could be classified in a table,  in families,  according to the number of protons in their nuclei. This number, called the atomic number, increases from top to bottom and from left to right on this table. The elements arranged in the same column have similar chemical properties.

This animation shows which elements were known at different periods of history:

  • 1700 (the death of Boyle)
  • 1787  (Lavoisier)
  • 1871 (Mendeleev)
  • At the present time
    • ]]>         <![CDATA[Mendeleev periodic table]]>
    First introduction to Mendeleev periodic table.
    ]]>         <![CDATA[Mendeleev]]>

    In 1869 the Russian chemist D. I. Mendeleev discovered that pure chemical elements (containing a single kind of atom) could be classified in a table, in families,  according to the number of protons in their nuclei. This number, called the atomic number, increases from top to bottom and from left to right on this table. The elements arranged in the same column have similar chemical properties.

    ]]>         <![CDATA[Atomic radius]]>
    The horizontal rows of the table are called periods and each of their elements have the same number of electron shells. The columns (groups or families) contain elements that have the same number of electrons in their outermost shell, which results  in  very similar  chemical properties. Some of these groups are highlighted.
    The atomic radius is a periodic property.
    ]]>         <![CDATA[C<sub>2</sub>H<sub>6</sub>]]>

    Ethane molecule (C2H6).

    ]]>         <![CDATA[NH<sub>3</sub>]]>

    Ammonia molecule (NH3).

    ]]>         <![CDATA[CH<sub>4</sub>]]>

    Methane molecule (CH4) and its Cram representation.

    ]]>         <![CDATA[C<sub>6</sub>H<sub>12</sub>]]>

    The cyclohexane molecule (C6H12) is used in the synthesis of nylon. The chair form of cyclohexane is the most stable conformation.

    ]]>         <![CDATA[H<sub>2</sub>O]]>

    Water molecule (H2O).

    ]]>         <![CDATA[CO<sub>2</sub>]]>

    Carbon dioxide molecule (CO2).

    ]]>