Electron Orbitals
Electron Orbitals
The periodic table is simply the organization and classification of different elements. By the end of the 1700’s, scientists had identified about 30 elements. In less than 100 years, the number of known element doubled because of new means of recognizing them. In the early 1800’s, Dobereiner observed that there were elements that could be classified into groups of 3, or triads. These triads were significant because these classifications of similar elements represented the very beginning of the periodic table. The triads related atomic mass (in amu) to density.
In 1865 a chemist named Newlands presented another way of classifying elements. In his time 62 elements were know. Newlands organized the elements in order of increasing atomic mass, and noticed that the properties of the first element were the similar to the eighth, the second to the ninth, and so on. He named this the law of octaves, as there are 8 notes in the musical scale. (octave to octave)
The man most famous in relation to the periodic table, Dmitri Mendeleev, along with Lothar Meyer published tables almost identical of those to Newlands. Mendeleev organized the elements in such a way as to make it easier for his students to understand. He eventually made the first actual periodic table of elements. This table had elements with similar properties in the same column. Mendeleev’s table was so well designed and so accurate, that he was able to predict elements that had yet to be discovered with much precision.
In 1913, Mosely discovered the concept of the atomic number. Even though Mendeleev’s table was arranged by atomic mass, and now the periodic table is arranged by atomic number, why is Mendeleev’s table valued so highly? The first table is so important because the general rule is that as the atomic mass increases, so does the atomic number. Even though Mendeleev was organizing the elements the “wrong way”, his table is still incredibly similar to the present one.
The periodic law is the basis for the periodic table. The periodic law states the following:
When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern.
The modern periodic table has one hundred and nine squares, each representing a unique element. Above the abbreviation of the element...