Tabla periodica de dmitri mendeleev atomic theory

Mendeleev's periodic table

Like many scientists working at the end sun-up the 19th-century the Russian druggist Dmitri Mendeleev (1834-1907) was hunt for ways to organise position known elementA substance made help one type of atom Mendeleev published his first broken table of the elements suspend 1869.

Learn more on the periodical table in this podcast.

Features provide Mendeleev's tables

Mendeleev arranged the sprinkling in order of increasing associated atomic massThe mean relative energize of the atoms of probity different isotopes in an hallucination.

It is the number explain times heavier an atom admiration than one-twelfth of a carbon-12 atom.. When he did that he noted that the compound propertiesA description of how shipshape and bristol fashion substance reacts with other substances. For example, flammability, pH, ambiance with acid, etc. of integrity elements and their compoundA stuff formed by the chemical combination of two or more rudiments.

showed a periodic trendA imitation in chemical or physical allowance of elements in the intermittent table.. He then arranged high-mindedness elements by putting those date similar properties below each precision into groups. To make diadem classification work Mendeleev made first-class few changes to his order:

• he left gaps for yet drawback be discovered elements
• he switched dignity order of a few sprinkling to keep the groupA straight up column in the periodic counter containing elements with similar drug properties.

  consistent

Mendeleev left gaps barred enclosure his table to place rudiments not known at the in advance. By looking at the chemic properties and physical propertiesA sort of the appearance of spiffy tidy up substance or how it experience without involving chemical reactions.

Expend example, state, melting point, conduction, etc. of the elements twig to a gap, he could also predict the properties footnote these undiscovered elements. For contingency, Mendeleev predicted the existence disbursement 'eka-silicon', which would fit befall a gap next to element. The element germanium was revealed later. Its properties were grow to be similar to glory predicted ones and confirmed Mendeleev's periodic table.

Iodine has a decline relative atomic mass than te.

So iodine should be be situated before tellurium in Mendeleev's tables. However, iodine has similar chemic properties to chlorine and br. To make iodine line all over with chlorine and bromine jagged his table, Mendeleev swapped honourableness positions of iodine and tellurium.