Arranges elements in order of increasing relative atomic mass. Mendeleev realised that the physical and chemical properties of elements were related to their atomic mass, ordering them so that groups of elements with mutual properties fell into vertical columns in his table. Due to the pattern in which the elements have been arranged, the table fails to indicate the element’s atomic number. While Mendeleev is most often regarded as the founder of the Periodic Table, his table was the first to gain credibility in society.
Mendeleev’s table provided the basis upon which the modern Periodic Table was formed. Mendeleev has failed to show the different chemical families. E.g. Noble Gasses. “Fond of card games, Mendeleev wrote the weight for each element on a separate index card and sorted them, as in solitaire. Elements with similar properties formed groups, which he placed in columns ordered by increasing atomic mass, founding the original Periodic Table.
Due to the method, which Mendeleev used to group the elements, his table had gaps in the horizontal rows. These gaps enabled him to predict that there were elements, which were still to be discovered, while his table, based on atomic mass, helped him to predict the missing element’s properties. Due to Mendeleev’s failure to explain the position of isotopes in his table, he was unable to assign a correct position to hydrogen. This is because Hydrogen, like halogens, is a diatomic molecule and combines with metals and non-metals to form covalent bonds. Hydrogen could therefore have been placed in Group I or Group VII. Mendeleev's homeland, named the "Mendeleev University of Chemical Technology" in Moscow, in his honour.
Mendeleev recognized that the “Periods” varied in length; he used periods of 7 and 17 elements. Despite the “Periods” later being proven to have lengths of 8 and 18, it still provided a basis, which could be added to and improved over time. Atomic masses do not increase in a regular manner going from one element to the next, making it impossible to predict exactly how many elements there were to be discovered between two elements.
Mendeleev was inconsistent with his results, with certain pairs of elements having higher atomic masses are found in the table before the elements with lower atomic masses. E.g. Argon (39.9) was placed before Potassium (39.1)
Theodor Benfey 1964 – Spiral Periodic Table
Theodor Benfey 1964 – PMI
Plus Minus Interesting Facts
Emphasizes the periods, so that when you move in spirals from the centre you get two periods of 8 elements, then two of 18 elements, then two of 32, and so on, making it easier to read. Despite ordering the elements in order of atomic number, Benfey has failed to mention both the atomic mass of the elements as well as their atomic number. Every spiral represents a “Period” on the traditional Periodic Table.
Clearly identifies the chemical families through the use of colour coding. Benfey has also used...