Periodic table of elements

                                                                                      The Periodic Table of Elements (or Mendeleev's Table) was designed in 1869 by Russian chemist Dmitry Ivanovich Mendeleev. The periodic table classifies all chemical elements according to their atomic number and chemical properties.

                                                                                      Definition of a chemical element

                                                                                      Set of atoms characterized by a defined number of protons in their nucleus. These atoms have different possible forms: isotopes (same number of protons and electrons but different number of neutrons).

                                                                                      Atomic number : number of protons and electrons of the element

                                                                                      Atomic symbol : universal representation of the element

                                                                                      The chemical elements of the periodic table are the building blocks of matter. Each element is defined by the number of protons in its atomic nucleus, which is also known as its atomic number.

                                                                                      All of the elements can be classified into one of four categories based on their electronic structure:

                                                                                      - The s-block elements, which are the elements in the first two rows of the periodic table. These elements include the alkali metals (such as lithium and sodium) and the alkaline earth metals (such as beryllium and magnesium). These elements have a valence electron in the s-orbital.
                                                                                      - The p-block elements, which are the elements in the last six rows of the periodic table. These elements include the nonmetals (such as hydrogen and carbon), the metalloids (such as silicon and boron), and the transition metals (such as titanium and chromium). These elements have a valence electron in the p-orbital.
                                                                                      - The d-block elements, which are the elements in the middle 10 rows of the periodic table. These elements include the transition metals (such as iron and copper). These elements have a valence electron in the d-orbital.
                                                                                      - The f-block elements, which are the elements in the last two rows of the periodic table. These elements include the lanthanoids and actinoids. These elements have a valence electron in the f-orbital.

                                                                                      Each element has unique chemical properties that are determined by its electronic structure. For example, the alkali metals are highly reactive, while the noble gases are chemically unreactive. The transition metals are known for their ability to form complex ions and colored compounds.

                                                                                      Elements can also be grouped into families or groups based on their chemical properties. For example, the halogens (such as chlorine and bromine) are known for their ability to form compounds with hydrogen, while the noble gases (such as helium and neon) are chemically unreactive.

                                                                                      Elements can also form compounds with one another, chemical reactions are the result of the interactions of electrons. The chemical properties of an element can change through chemical reactions, through the exchange or sharing of electrons with other elements.

                                                                                      Mendeleeev

                                                                                      Dmitry Ivanovich Mendeleev (or Dmitry Mendeleev) designed the periodic table in 1869. He is a Russian chemist. He was born on February 8, 1834 in Tobolsk (Siberia, Russia). He died on February 2, 1907 in Saint Petersburg.

                                                                                      Dmitri Ivanovich Mendeleev was a Russian chemist and physicist, born on February 8, 1834 and died on February 2, 1907. He is best known for his contribution to the creation of the periodic table of elements, a fundamental tool for the study of chemistry.

                                                                                      In 1869, Mendeleev published his "Periodic Table of Chemical Elements" in which he organized the known elements at the time based on their similar physical and chemical properties, arranging them in order of increasing atomic number. He also predicted the existence of undiscovered elements based on gaps in his table, giving them predicted properties and predicting that they would have similar properties to those that surrounded them in the table. The predicted elements were later discovered, confirming the validity of his classification.

                                                                                      Mendeleev's work on the periodic table was not only a major breakthrough in the field of chemistry, but also had a profound impact on other sciences such as physics, materials science and geology. His table enabled scientists to understand the underlying patterns of the properties of elements and to predict the properties of unknown elements. The periodic table is now widely used in many areas of science and is considered one of the most important tools for understanding the properties of matter.

                                                                                      Mendeleev's work also extended beyond the periodic table. He studied the chemistry of liquids and gases, thermochemistry, and the chemistry of solutions. He was one of the first to use experimental data to establish chemical laws. He studied the chemistry of the rare earths and discovered the new element germanium. He also studied the chemistry of combinations of elements with hydrogen, leading to the creation of the classification of hydrides. He also studied the properties of compounds and was able to predict the properties of new compounds.

                                                                                      In recognition of his contributions to science, Mendeleev was elected as a member of many scientific societies, including the Royal Society in 1890. He received many awards and honors, including the Royal Society's Davy Medal in 1892 for his work on the periodic table. He was also awarded an honorary doctorate from the University of Würzburg and the Rumford Medal of the Royal Society in 1906. He was made a foreign member of the Royal Society of London, the Royal Society of Edinburgh, and the Academy of Sciences of the Institute of Bologna.

                                                                                      Mendeleev was not only a great scientist but also a skilled teacher and a respected public figure. He was a professor at the University of St. Petersburg and later at the St. Petersburg Technological Institute, where he trained many students who went on to become successful scientists themselves. He was also actively involved in the development of science education in Russia and was a strong advocate for the establishment of technical schools and universities.

                                                                                      In conclusion, Dmitri Mendeleev was an outstanding chemist and physicist who made significant contributions to the field of chemistry, particularly with his development of the periodic table of elements. His work had a profound impact on many areas of science and continues to be an important tool for understanding the properties of matter. He was also a gifted teacher and a respected public figure who played an important role in the development of science education in Russia.