Download Periodic Table Element Pattern

The history of the periodic table reflects over a century of growth in the understanding
of chemical properties, and culminates with the publication of the first actual periodic
table by Dmitri Mendeleev in 1869.[1] While Mendeleev built upon earlier discoveries by
such scientists as Antoine-Laurent de Lavoisier, the Russian scientist is generally given
sole credit for development of the actual periodic table itself.
The table itself is a visual representation of the periodic law which states that certain
properties of elements repeat periodically when arranged by atomic number. The table
arranges elements into vertical columns (Groups) and horizontal rows (Periods) to
display these commonalities.
Elemental ideas from ancient times
People have known about some chemical elements such as gold, silver and copper from
antiquity, as these can all be discovered in nature in native form and are relatively simple
to mine with primitive tools.[2] About 330 B.C Aristotle proposed that everything is made
up of a mixture of one or more of four "roots" (originally put forth by the Sicilian
philosopher Empedocles), but later renamed elements by Plato. The four elements were
earth, water, air and fire. While the concept of an element was thus introduced, Aristotle's
and Plato's ideas did nothing to advance the understanding of the nature of matter
Antoine Laurent de Lavoisier
Lavoisier's Traité Élémentaire de Chimie (Elementary Treatise of Chemistry, 1789,
translated into English by Robert Kerr) is considered to be the first modern chemical
textbook. It contained a list of elements, or substances that could not be broken down
further, which included oxygen, nitrogen, hydrogen, phosphorus, mercury, zinc, and
sulfur
was the first scientist to make a periodic table much like the one we use today.
Mendeleev arranged the elements in a table ordered by atomic weight, corresponding to
relative molar mass as defined today. It is sometimes said that he played "chemical
solitaire" on long train rides using cards with various facts of known elements.[9] On
March 6, 1869, a formal presentation was made to the Russian Chemical Society, entitled
The Dependence Between the Properties of the Atomic Weights of the Elements. His table
was published in an obscure Russian journal but quickly republished in a German journal,
Zeitschrift für Chemie (Eng., "Chemistry Magazine"), in 1869. It stated:
1. The elements, if arranged according to their atomic weights, exhibit an apparent
periodicity of properties.
2. Elements which are similar as regards to their chemical properties have atomic weights
which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly
(e.g., K, Rb, Cs).
3. The arrangement of the elements, or of groups of elements in the order of their atomic
weights, corresponds to their so-called valencies, as well as, to some extent, to their
4.
5.
6.
7.
8.
distinctive chemical properties; as is apparent among other series in that of Li, Be, Ba, C,
N, O, and Sn.
The elements which are the most widely diffused have small atomic weights.
The magnitude of the atomic weight determines the character of the element, just as
the magnitude of the molecule determines the character of a compound body.
We must expect the discovery of many yet unknown elements–for example, elements
analogous to aluminium and silicon–whose atomic weight would be between 65 and 75.
The atomic weight of an element may sometimes be amended by a knowledge of those
of its contiguous elements. Thus the atomic weight of tellurium must lie between 123
and 126, and cannot be 128. (This was based on the position of tellurium between
antimony and iodine whose atomic weight is 127. However Moseley later explained the
position of these elements without revising the atomic weight values — see below.)
Certain characteristic properties of elements can be foretold from their atomic weights.
This version of Mendeleev's periodic table from 1891. It is lacking the noble gases
Scientific benefits of Mendeleev's table
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
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Mendeleev predicted the discovery of other elements and left space for these new
elements, namely eka-silicon (germanium), eka-aluminium (gallium), and eka-boron
(scandium). Thus, there was no disturbance in the periodic table.
He pointed out that some of the then current atomic weights were incorrect.
He provided for variance from atomic weight order.
Shortcomings of Mendeleev's table
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
His table did not include any of the noble gases, which were discovered later. These
were added by Sir William Ramsay as Group 0, without any disturbance to the basic
concept of the periodic table.
There was no place for the isotopes of the various elements, which were discovered
later.
[edit] Lothar Meyer
Unknown to Mendeleev, Lothar Meyer was also working on a periodic table. Although
his work was published in 1864, and was done independently of Mendeleev, few
historians regard him as an equal co-creator of the periodic table. For one thing, Meyer's
table only included 28 elements. Furthermore, Meyer classified elements not by atomic
weight, but by valence alone.
References
1. ^ IUPAC article on periodic table
2. ^ Scerri, E. R. (2006). The Periodic Table: Its Story and Its Significance; New
York City, New York; Oxford University Press.
3. ^ a b c "A Brief History of the Development of Periodic Table".
http://www.wou.edu/las/physci/ch412/perhist.htm.
4. ^ Leicester, Henry M. (1971). The Historical Background of Chemistry; New
York City, New York; Dover Publications.
5. ^ Annales des Mines history page.
Periodic Table Element Pattern
The pattern of elements in the periodic table reflects the progressive filling of electronic
orbitals. The two columns on the left—the alkali metals and alkaline earths—show the
addition of 1 and 2 electrons into s-type subshells.
The loss of these s-subshell valence electrons explains the common +1 and +2 charges on ions of these
elements, except for helium, which is chemically inert.
The six elements from boron through neon show the insertion of electrons into the lowest-energy p-type
subshell. (See Figure 1 .)
Figure 1Filling of the 2 p subshell.
1. The position of hydrogen is still not settled since it shows properties of both alkali metals as well as
halogens.
2. Lanthanides and actinides are not accommodated in the main body of the periodic table
Periods
There are seven periods in the periodic table and each period starts with a different principal quantum
number.
The first period corresponding to 'n' = 1 consists of only two elements hydrogen (1s 1) and helium (1s2). This
is because the first energy shell has only one orbital (1s), which can accommodate only two electrons.
In the second period corresponding to 'n' = 2, there are four orbitals (one '2s' and three '2p') having a
capacity of eight electrons and so contains eight elements. This period starts with lithium (Z = 3) with
electron entering the '2s' orbital and ends with neon (Z = 10) where the second shell is complete (2s 2 2p6).
In the third period corresponding to 'n' = 3, there are nine orbitals (one '2s' three '2p' and five '3d'). As '3d'
orbitals are higher in energy, they are filled after the '4s' orbitals. This period involves filling of only four
orbitals ('3s' and '3p') containing eight elements. It starts with sodium (Z = 11) with electron entering the '3s'
orbital and ends with argon (Z = 18) where the third shell is partially complete (3s 2 3p6).
The fourth period corresponding to 'n' = 4, consists of filling of one '4s' and three '4p' orbitals. The '4d' and
'4f' orbital are higher in energy than the '5s' orbitals and are filled later. The five '3d' orbitals have energies in
between '4s' and '4p' orbitals and so are filled accordingly. Totally nine orbitals are filled and therefore, there
are eighteen elements in this period starting from potassium with electron entering the '4s' orbital (Z = 19) to
krypton (Z = 36) where the third shell gets completed (4s 2 3d104p6).
In the fifth period there are 18 elements like the fourth period. It begins with rubidium (Z = 37) with the filling
of '5s' orbital and ends with xenon (Z = 54) with the filling of '5p' orbital.
The sixth period contains 32 elements (Z=55 to 86) and the successive electrons enter into '6s', '4f', '5d' and
'6p' orbitals in that order. It starts with caesium and ends with radon.
The seventh period, though expected to have 32 elements is incomplete and contains only 19 elements at
present.
Number of elements in each period
There is a periodicity occurring at regular intervals of 2, 8, 8, 18, 18 and 32 and so the numbers 2, 8, 18 and
32 are called magic numbers. The first three periods are called short periods while the other three periods
are called long periods.
Groups
The vertical column in the periodic table is called as group. There are 18 groups in the long form of the
periodic table and they are numbered from 1 to 18 in the IUPAC system. In the old system of naming they
are numbered as I to VIII with A and B groups. This convention is followed in many places
Merits of the long form of the periodic table

This classification is based on the most fundamental property of the elements - the atomic number, so it
is more accurate.
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With the atomic number as the basis of this classification, the position of isotopes in one place is
justified.
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The systematic grouping of elements into the four blocks of 's', 'p', 'd' and 'f ' has made the study of
elements simpler.

The electronic configuration determines the properties of the elements. The position of elements
governed by this feature is useful in studying the properties of elements.

The position of the elements, which were misfit on the basis of atomic mass is now justified on the basis
of atomic number.
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The lanthanides and actinides have been placed separately due to their properties different from other
groups.

The whole table is easy to remember and reproduce in terms of electronic configuration and properties
of the elements.
Demerits of the long form of the periodic table
Although the long form of the period table has been able to help in systematic studying the elements to a
great extent, it has some minor defects:

Hydrogen resembles both the alkali metals and halogens. But it has been placed with the alkalis.
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The lanthanides and actinides have not been placed in the main body of the table.
Some people have found the simple long-form periodic table unsatisfactory for
aesthetic reasons. The possibility of producing a “best” form has been discussed
recently (Scerri, 2008). Just as the d-transition elements were introduced into the
old short form of the table to make a long form (figure 1), the actinoids and
lanthanoids have been further inserted to make an even longer form (figure 2). A
plethora of shapes have been proposed for the table, both two- and threedimensional, and triangular or circular or square. For a selection see van Spronsen,
1969. None is ultimately the “correct” or “best” shape. Teachers have sometimes
found the long form unsatisfactory for instructing students in detail, and various
longer forms are often suggested, for example, to try to regularize the treatment of
the lanthanoids and actinoids. For these and related reasons, new forms of the
periodic table are being continually proposed. A “left-step” example has recently
been mentioned (Scerri, 2008). This proposal is shown in figure 3. There are many
others. However, it is really the person using the table who must determine if it
meets his or her requirements.
Figure 2. A long, long form of the periodic table which retains the approved 1–
18 Group numbering but omits any individual group designation for the
lanthanoids and actinoids.
As an inorganic chemist with experience in nomenclature, I receive many of these
new versions, often with a request that IUPAC consider formally approving them. So
far, our invariable response has been to refuse, regardless of the merit of the
proposal. The Division of Nomenclature and Structure Representation has recently
reaffirmed this position.
Figure 3. A left-step form of the periodic table with the 1–18 Group numbering,
adapted from Scerri (2008).
Some of the proposals for the table are baroque in the extreme, but that has not
been the direct reason for refusing to adopt them. The proponents are often teachers
who wish to use a periodic table to facilitate their own teaching of electronic
structures. This is eminently reasonable, because it is not unexpected that a table
based originally on atomic weights does not accord satisfactorily with every nuance
of electronic structure. However, in this context, IUPAC does not concern itself with
electronic structure. IUPAC’s primary concern is with unequivocal and unambiguous
communication.