IT'S ALL IN THE FAMILY
Think about your family today. It may consist of you, one or two adults who are your parents or guardians, and one or more siblings. You may have an extended family including one or more grandparents, aunts, uncles, and cousins. All of you share a family relationship. You may share certain characteristics. Has anyone ever told you that you look, walk, or talk like your mother or father, grandmother or grandfather? You might even have a family member who has an interest in genealogy and who has mapped out your family history, including a chart known as a family tree. If you have seen such a tree, you know that each name represents a person, and that some individuals on the tree are more closely related than others.Now, think of the periodic table of elements. It too is a chart that shows relationships. Like many families, certain individual elements in this chart share characteristics, some more closely than others. However, all are related
Periodic Table formulations from the years before 1900, by date:
1000BC Elements Known To The Ancients
450BC Classical Elements
1682 Kenelm Digby's A Choice Collection of Rare Secrets
1718 Geoffroy’s Affinity Table
1778 Diderot's Alchemical Chart of Affinities
1782 de Morveau's Table of Chemically Simple Substances
1789 Lavoisier's Table of Simple Substances
1800 Elements Known in The Year 1800
1803 Dalton's Postulates About The Elements
1808 John Dalton's Elements
1831 Daubeny's Teaching Display Board of Atomic Weight
1843 Gmelin's System
1850 Johann Dobereiner's Triads
1862 Telluric Helix or Screw
1862 Meyer's Periodic System of 1862
1864 Newlands' Octaves
1864 William Odling's Table of Elements
1864 Naquet's Families of Elements
1867 Hinrichs’s Spiral Periodic System
1868 Handwritten draft of the first version of Mendeleev's Periodic Table
1868 Meyer's "Lost" Table
1869 Mendeleev's Tabelle I
1869 Mendeléeff's Vertical Table (Q&Q's Spelling)
1870 Meyer's Periodic Table
1870 Baumhauer's Spiral
1871 Mendeleev's Tabelle II
1871 Mendeleev's Predicted Elements
1872 Meyer's Spiral System
1881 Spring's Diagram
1882 Bayley's Periodic System
1882 Brauner's 1882 Periodic Table
1886 Crookes' Periodic Table
1887 Flavitzky's Arrangement
1892 Bassett's Vertical Arrangement
1892 Bassett Dumb-Bell Form
1893 Rang's Periodic Table
1895 Retger's Periodic Table
1895 Thomsen's Periodic Table
1898 Crookes' vis generatrix
THE TRIAD MODEL
A German scientist, Johan Dobereiner (1780-1849), tried to classify elements into
smaller and simpler subgroups. In 1829, he observed that elements with similar
physical and chemical properties fall into groups of three. He called these related
groups of three elements triads.
One of these triads included chlorine, bromine, and iodine; another consisted of
calcium, strontium, and barium. In each of these triads, the atomic weight of the
intermediate element is approximately the average of the atomic weights of the other
two elements. The density of that element is approximately the average of the
densities of the other two elements.
The problem with this arrangement was that Dobereiner’s model became outdated as
new elements were identified. A good model is able to incorporate newly understood
information. Dobereiner’s Triad Model was not useful, since several newly discovered
elements did not “fit” into it.
Johan Dobereiner 
THE LAW OF OCTAVES
In 1864, an English chemist, John Newlands, arranged the known elements in increasing order of their atomic weights. He noted that chemically similar elements occurred every eight elements. Lighter sodium was like potassium, and so on through pairs of elements until fluorine and chlorine, the seventh pair. Since potassium followed fluorine (the noble gases
had not yet been discovered), Newlands called the repeating pattern the Law of Octaves since the eighth element
resembled the first. His Law of Octaves was based on this observation.
However, there were some deficiencies in Newland’s proposed arrangement. Several known elements did not fit his pattern.
Newlands did not allow for the possibility of the discovery of additional elements at a later date. Further, he did not question
whether all the atomic masses known to that date were correct. Newlands’ Law of Octaves was not a good model for
explaining the relationship among the elements.
Newlands' Octaves
One of the first attempts at a periodic table, known as "Newlands octaves", arranged the known elements by atomic weight. Newland noticed that if he broke up his list of elements into groups of seven – starting a new row with the eighth element – the first element in each of those groups had similar chemistry. More here.H F
Seeing the word octave applied to this table may lead one to think that Newlands recognised periods of eight elements with repeating properties, as we do with the modern periodic table,
However, each sequence of Newlands' octaves contain only seven elements. Count the columns! In Newlands' day the group 8 (18) rare gas elements, He, Ne, Ar, Kr & Xe, had not yet been discovered.
To Newlands, Li to Na is an octave of eight elements, the eighth element repeating the properties of the first.
A B C D E F G A
1862 Meyer's Periodic System of 1862
In his book, The Periodic Table: A Very Short Introduction, Eric Scerri writes how Lothar Meyer devised a partial periodic tables consisting of 28 elements arranged in order of increasing atomic weight in which the elements were grouped into vertical columns according to their chemical valences:
MENDELEEV
In the mid-1800s, most chemists worldwide were convinced that the elements existed in
families that had similar physical and chemical properties. However, there was no widely
accepted chart that explained relationships in chemical properties among chemical
groups. The periodic table, an information organizing tool that we take for granted today,
began as a simple question in the mind of a Russian scientist, Dmitrii I. Mendeleev
(1843-1907). What is the relationship of the elements to one another and to the chemical
families to which they belong?
Mendeleev's passion for understanding the families of elements took him into previously
uncharted territory. He felt that the newly understood atomic mass measurements would
have greater significance once scientists clearly understood the relationships among the
elements. Mendeleev wrote his ideas into the chemistry textbooks from which he taught.
In
Principles of Chemistry
, published in 1869, Mendeleev introduced a concept he called
the Periodic Law that stated:
He subsequently published several versions of a periodic table of the elements, including all elements known at that time.How was Mendeleev able to chart the relationships among the 63 known elements? It all started in a game of cards.
A GAME OF CARDS
In order to understand the properties of the known elements and their relationships to one another, Mendeleev developed a card game. He wrote out the properties of each element on a different card and spent a great deal of time arranging and rearranging them. He was looking for patterns or trends in the data on the cards. His friends called this game “Patience.” Mendeleev first arranged all the cards from lowest to highest atomic mass. The lightest element known in Mendeleev’s time was hydrogen. Its properties were not like any other known element. So Mendeleev decided to leave it out of his game. Scientists who are initially struggling to understand a large mass of data commonly ignore, at least for a time, those data points that seem too different from the others. These unusual instances are termed outliers. Whether or not outliers can eventually be explained by a model often makes or breaks the scientific theory from which the model derives.http://genesismission.jpl.nasa.gov/educate/scimodule/UnderElem/UnderElem_pdf/HistOverST.pdf
