PowerPoint presentation on contribution of various scientist was development of periodic table.
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1. ORIGIN OF THE CHEMICAL NAMES AND SYMBOLS • Alchemy refers to both an early form of the investigation of nature and an early philosophical and spiritual disciplines. Alchemists were known in different aspects and one of these is their popular culture, the process of changing some elements into gold.
2. • They were the first to introduce the symbols of the elements in the Middle Ages. This practice of using symbols has influenced modern chemists and helped them to work easily with the elements.
3. • Modern chemists use symbols for each element to facilitate writing and for convenience. They assigned each element unique symbols. This system of chemical symbols was invented by Jons Jacob Berzelius.
4. • Each element’s symbol has a different origin. Some of the element’s symbol are either the initial letter of the element or a combination of the first or another letter from the Latin or English name of the elements. SOME ELEMENTS WITH SYMBOLS DERIVED FROM ITS INITIAL LETTER SOME ELEMENTS WITH SYMBOLS DERIVED FROM THE COMBINATION OF ITS FIRST AND ANOTHER LETTER SYMBOL NAME SYMBOL NAME B BORON Br BROMINE I IODINE Ir IRIDIUM C CARBON Cl CHLORINE H HYDROGEN He HELIUM N NITROGEN Cr CHROMIUM O OXYGEN Zn ZINC K POTASSIUM (LATIN; KALIUM) Fe IRON (LATIN; FERRUM)
5. • Aside from Latin and English names, some elements’ names and symbols were derived from the scientists’ or discoverers’ names such as Bohrium (Bh) named after Neils Bohr and Curium (Cu) for Marie Curie . Countries or places where it was discovered (example, Californium derived from California, mythology (example, Palladium derived from Pallas Athena), planets (Plutonium from the planet Pluto, its Greek (like Xenon, from the Greek word xenos; “foreign”) or German names (like Zinc from German zinken, “point”), colors (example Indium from the Greek word indium, “indigo”). majority of the elements in the periodic table have symbols consisting of two letters with the first letter capitalized. As chemists discovered more elements, they began to observe the arrangement of each element through patterns in their properties. These patterns helped the chemists decipher the elements better.
6. ORIGIN OF THE PERIODIC TABLE
7. ANTOINE LAVOISIER’S FIRST CLASSIFICATION • In 1789, Antoine Lavoisier, a French physicist-chemist published a book that contained the classification of elements based on their similar properties. He arranged the elements into groups. Unfortunately, his work did not progress until his death in 1794.
8. DÖBEREINER’S TRIAD • In 1817, Johannes Wolfgang Döbereiner, a German chemist, studied three elements and noticed similarities among the properties of metals such as Ca, Ba and Sr. He continued to study another group of three elements, Cl, Br and I. Döbereiner predicted that there is closeness among the atomic masses (traditionally called atomic weight) of the said elements.
9. • He concluded that the atomic mass and the density of the middle element in each triad is the approximate average if the masses and densities of the first and the third elements. Attempts were made to arrange the elements into triads in 1850. Nevertheless, more reliable measurements were introduced and speculations on the atomic mass of the middle element became less accurate.
10. DE CHANCOURTOIS’S TELLURIC HELIX • In 1863, A.E. Beguyer de Chancourtois had the idea to plot the elements in a spiral around the surface of the cylinder divided into 16 vertical sections according to the elements’ atomic masses. In every vertical strip, the elements with the same physical and chemical properties were grouped together. He called his device telluric helix.
11. • He stated from the results of his experiments that the properties of elements were the same as the properties of numbers. His idea seemed tenable enough at first but failed to muster support.
12. NEWLANDS’ OCTAVES • Although Döbereiner’s triads proved to be significant and de Chancortois idea did not gain support at that time these were used as bases for seeking further classification of elements. In 1869, John Newlands, an English chemist presented another way of classifying elements.
13. • He arranged all the elements known at that time in order of their atomic masses beginning with lithium and noted that the eighth element has similar properties to the first element, the ninth to the second, and the tenth to the third and so on. He compared their relationship to the octaves of musical notes. He then called this pattern the Law of Octaves.
14. MEDELEEV’S PERIODIC TABLE AND MEYER’S PERIODIC PROPERTY GRAPH • In 1869, Russian chemist Dmitri Ivanovich Medeleev and German chemist Julius Lothar Meyer, working independently presented closely identical version of arranging the elements based on their increasing properties. Both scientists proposed the periodic law which states that the properties of elements are periodic functions of their atomic masses. Dmitri Mendeleev Lothar Meyer