Development of Modern Periodic Table and Limitations

The periodic table refers to an arrangement of the chemical elements that are organised on the basis of their atomic numbers, their electron configurations, and their recurring chemical properties. Elements are presented in the periodic table in the order of the increasing atomic number. The standard form of the table contains a grid that has rows called periods and columns called groups. 

The history of the periodic table is a reflection of more than two centuries of growth to understand the chemical and physical properties of the elements. The major contributions to the development of the periodic table were made by Antoine-Laurent de Lavoisier, John Newlands, Johann Wolfgang Döbereiner, Julius Lothar Meyer, Glenn T. Seaborg, Dmitri Mendeleev, and many others. In this article, we will learn in detail about the history of the periodic table, who invented the periodic table, and the evolution of the periodic table.

Brief History of Periodic Table

The periodic table is for many people the symbol of chemistry. It is a single image in a tabular form that contains all the known elements in the universe that are combined into an easily readable table. There are many different patterns present in the table as well. All of these elements seem to fit together and connect to each other to form a readable table and, in turn, the image of chemistry. 

The thought of elements first came around in 3000 B.C. The Greek philosopher Aristotle had the idea that everything on the Earth was made up of these elements. In ancient times, elements like gold and silver were easily accessible, however, the elements which Aristotle chose were Earth, Water, Fire, and Air.

In 1649 the idea of elements took a big step when Hennig Brand was the first person to discover a new element called phosphorus. Brand was an alchemist who was in search of the Philosopher's Stone, or an object which would turn any kind of ordinary metal into gold. In his search, he had tried everything, including distilling the human urine. When this experiment was carried out Brand discovered a glowing white coloured rock. This was the new element he had decided to call phosphorous. The alchemists and scientists of this enlightenment period added varying amounts of knowledge to several ideas about different elements. In 1869 there were already 63 elements that were discovered. With every new element which was found, scientists began to realize that there were some sorts of patterns that were developing and some started to put these elements into a table.

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Doberiener’s Triads

The German chemist named Johann Dobereiner in the year 1800 first observed that there were similarities in the elements based on their properties. He saw that there were groups that consisted of three elements or triads which have much similar chemical and physical properties.

In every group, the atomic weight of the middle element was noted to be half the sum of the atomic weight of the other two elements of the group. Properties of the middle element also lied in the middle of both the other elements. Dobereiner named this method of grouping as the law of triads. Later on, it was found that this law of triads was not true for each element and hence, it was not proven to be successful.

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Newland’s Octaves

In the year 1865, after the failure of Doberiener’s law of triads, the English chemist John Alexander Newlands introduced the law of octaves. According to him, the elements can be arranged in ascending order according to their atomic weights. He also admitted that in this arrangement every eighth element in a row had the same properties as that of the first element of the same row, which depicts the octaves of music. This law was also not successful since it was only true for the elements up to calcium.

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Mendeleev’s Periodic Table

The actual development in the periodic table happened after the development of Mendeleev’s periodic table. He introduced a law that stated that the properties of a given element are the periodic function of their atomic masses. He then arranged elements in periods or horizontal rows and groups or vertical columns in increasing order according to their atomic weights. The vertical column contains the elements which have similar properties.

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Modern Periodic Table Introduction 

In chemistry, the periodic table of the elements is the organised pattern of all the chemical elements in increasing order of atomic numbers that is the total number of protons in the atomic nucleus. Chemical elements are arranged in a recurring pattern called the periodic law in their properties, in which elements in the same column group have similar properties. The first discovery of periodic elements was made by Dmitry I. Mendeleyev in the mid-19th century.

History of the Periodic Table

Atomic theory is discovered by the ancient Greek philosophers and those of Hellenistic Egypt. In this theory, all substances were made of fundamental building blocks. All these fundamental blocks were called atoms, which is derived from the Greek word meaning indivisible. The atomic theory defines various properties of matter by assigning attributes to atoms that match the attributes of the different matter that are combined to form, such as slipperiness, liquidity, color, and cohesiveness. Philosophers described the surrounding by property and function, a type of approach that led to the development of the periodic table of elements. 

And then in the Middle Ages, there was a generation of making gold and silver from lead but all these efforts were wasted because their investigation has ultimately led to a systematic understanding of the chemical world. Then the Alchemists were influenced by international trade, Chemical knowledge spread across cultures, and by the middle of the 18th century, 33 elements were discovered. At the start of the 19th century, Joseph Proust and his team were demonstrating the Law of Definite Proportions experimentally. This was the scientific evidence that matter existed in pure compounds as opposed to just mixtures of any proportion. These observations about elements gave a base to the atomic theory and demanded a systematic method of organizing the elements.

Limitations of Periodic Table

• The atomic number of an element of a periodic table never changes, it means that the number of protons in the nucleus of every atom in an element is always the same.

• Every atom of a periodic table have a mass number that is derived as : 

Number of neutrons + Number of protons = Mass number

• Periodic table element or isotope’s atomic number defines the number of protons in its atoms.

• Periodic table element or isotope’s mass number defines the number of protons and neutrons in its atoms.

Conclusion

This is how the modern periodic table was developed by making the different postulates as a foundation. The contribution of the scientists has been contributed to the formation of this table where all the elements we know can be accommodated. Find out the conceptual differences of all these postulates so that you can understand how this modern periodic table developed in due course of time.