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About this sample
About this sample
Words: 766 |
Pages: 2|
4 min read
Published: Jan 29, 2019
Words: 766|Pages: 2|4 min read
Published: Jan 29, 2019
The periodic table has an incredibly vast history of development, requiring the hard work of many scientific geniuses in the world. It’s creation is also linked with the discover of the chemical elements. The first person to discover a new element was Hennig Brand, a bankrupt german merchant. Hennig Brand tried to replicate the mythical Philosophers a Stone, an object that was supposed to turn normal bass metals into gold. In 1649 he experimented with distilled human urine, producing a glowing white substance which he named phosphorus. He kept his discovery secret until Robert Boyle rediscovered phosphorus in 1680. In 1661, Robert Boyle also defined an element as “a substance that cannot be broken down into a simpler substance by a chemical reaction”. That explanation served for three centuries and lasted until the discovery of subatomic particles.
Antoine Laurent de Lavoisier, a french scientist wrote the “Elementary Treatise of Chemistry”. It is considered to be the first modern textbook about chemistry which included a list of substances that Lavoisier thought could not be broken down further.
In 1817, Johann Wolfgang Döbereiner began to try to formula one of the earliest attempts to classify the elements. In 1829, he found he could form some of the elements into groups of three. With the elements of each group having related properties. He called these groups triads. The definition of the triad law is “Chemically analogous elements arranged in increasing order of their atomic weights formed well marked groups of three called Triads in which the atomic weight of the middle element was found to be generally the arithmetic mean of the atomic weight of the other two elements in the triad.”
In 1862, a french geologist, Alexandre-Emile Béguyer de Chancourtois devised an early form of periodic table, which he named the “telluric helix”, after the element tellurium. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight. Using this table, Alexander-Emile Béguyer de Chancourtois saw that elements with similar properties lined up vertically.
In 1864, the English chemist John Newlands classified the sixty-two known elements into eight groups (the law of octaves), based on their physical properties. John Newlands discovered that many pairs of similar elements existed. Although they differed by multiples of eight in mass number. John Newlands was also the first to assign them an atomic number.
Dmitri Mendeleev, a Russian chemist was the first scientist to produce a periodic table similar to the one used today. Dmitri Mendeleev arranged the elements by atomic mass. Dmitri Mendeleev stated in a presentation that:
1 The elements, if arranged according to their atomic mass, 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 masses, corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F.
4 The elements which are the most widely diffused have small atomic weights.
5 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.
6 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.
7 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.
8 Certain characteristic properties of elements can be foretold from their atomic masses.
Frederick Soddy in 1913 found that although some “elements” during that time emitted different radiation, many of them were similar in their chemical characteristics so they shared the same place on the periodic table. They became known as isotopes.
Glenn T. Seaborg, a scientist discovered that during his Manhattan Project in 1943, he experienced unexpected difficulties in isolating the elements americium and curium. Glenn T. Seaborg wondered if these elements belonged to a difference series, seeing as how they had different chemical properties to what was expected. In 1944, he proposed a significant change to Dmitri Mendeleev's table: the actinide series. The actinide concept of heavy element electronic structure predicted that the actinides, including the first few transuranium elements, would form a transition series analogous to the rare series of lanthanides elements.
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