http://podzamcze-dobczyce.pl/index.php/pl/sala-bankietowa/assets/js/jquery-ui.datepicker.js At the end of the article, you will able to describe – History of the Periodic Table, Parts of the Periodic Table, Properties, and Facts. Let’s start discussing one by one.
- A shopkeeper dealing in different items say stationary, cosmetics, confectionery, etc. place things of one type at one place.
- In the library, books of one subject are placed in one almirah.
rencontre ado 27 This is done for convenience and to make things easy and simple. Similarly, the properties 118 elements difficult to study. So, there is need of a long form of a table.
http://mediaeffectivegroup.pl/?jiiopaa=opcje-binarne-godziny-handlu&686=62 History of the Periodic Table
In order to study elements in an organized manner, they need to be classified.
- Dobereiner, a German chemist, grouped the elements in triads (groups of three elements), in such a way that
|http://fisflug.is/?yrus=avatrade-opzioni-digitali&e8c=6f The middle element of the triad had both atomic mass and properties roughly equal to the average of the other two elements of the triad.|
- Examples: Ca (40), Sr (88), Ba (137): Average of Ca and Ba is equal to= Sr (88.5)
- Li (7), Na (23), K (39) : =Average of Li and k is equal to= K (23).
However, this method was soon discarded, since only a few elements known at that time could be arranged in such triads.
2. Newland, an English scientist, gave the law of octaves, which states that:
|follow site When elements are arranged in an increasing order of atomic mass, every eighth element beginning from any element resembles the first element in its physical and chemical properties.|
This method was also discarded since it failed to accommodate the heavier elements.
3. Dmitri Mendeleev, a Russian chemist published a table of elements, which states that
|go site The properties of elements are the periodic functions of their atomic masses.|
He even predicted the existence of those elements which were not discovered at that time. The whole table arrangement in vertical columns known as groups and horizontal rows are known as periods. He arranged the elements in order of their increasing atomic masses.The table could not explain the trend in atomic mass change. Mendeleev again published a new table of elements which is divided into 4 blocks. This table is called as long form of a table.
http://totaltechav.com/merdokit/4669 - Se volete conoscere le opzioni binarie e capire come iniziare passo dopo passo, non vi resta che leggere la nostra guida alle Parts of the Periodic Table
A total of 118 natural and synthetic elements are known. It becomes difficult to study the properties of elements and their compounds individually because of their vast number. So there is a need of a modern long form of the table.
- Alkali metals
- Alkali Earth Metals
- Transition metals
- Inert or Nobel gases
- Lanthanide elements
- Actinide elements
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The few defect left behind in the table of elements were removed by Henery Mosley. He put forward the modern periodic table and states that the properties of elements are a periodic function of their atomic number. Important features of the modern long-form table are listed below:
- It is based upon the atomic number which is the most fundamental property of the element.
- The position of an element in the table is related to the electronic configuration of the elements.
- It is simple and easy to reproduce.
- The elements present in any vertical column resemble closely with one another.
- Division of the elements has helped to understand their properties easily.
- The properties of the elements in periodic table blocks can be predicted even before their discoveries.
- It reflects the similarities, differences, and trends in physical and chemical properties more clearly. Thus it is an ideal arrangement for the classification of the elements.
- There is no need for providing a separate place to isotopes of the elements as they have the same atomic number.
- The position of the transition elements is justified in the light of their electronic configuration. These elements have their penultimate shell incomplete.
source link Periodic Table Facts
- No such elements in the table which start with J letter.
- Carbon having atomic 6 has the only elements that have the tendency of forming millions of compounds in the world of chemistry.
- Atomic no 87 francium is the rarest element on earth.
- Scientists discover the helium element when observing the sun carefully.
- Properties of elements in the modern long-form table are based on the electronic configuration.
This is all about the basics of – follow url History of the Periodic Table, Parts of the Periodic Table, Properties, and Facts.