Russian chemist Dmitri Mendeleev published a periodic table in 1869. It arranges the chemical elements according to their recurring properties. The number of each element corresponds to the number of protons in its nucleus. According to their shared physical and chemical properties, the elements can be classified into the major categories of metals, metalloids and nonmetals.
About Periodic table in brief
Russian chemist Dmitri Mendeleev published a periodic table in 1869. It arranges the chemical elements according to their recurring properties. The number of each element corresponds to the number of protons in its nucleus. The modern periodic table provides a useful framework for analyzing chemical reactions, and is widely used in chemistry, physics and other sciences. The organization of the periodic table can be used to derive relationships between the properties of the various elements, and to predict chemical properties and behaviours of newly synthesized elements. According to their shared physical and chemical properties, the elements can be classified into the major categories of metals, metalloids and nonmetals. Since the mid-20th century the term metalloid has been widely used to refer to elements with intermediate or borderline properties between metals and non Metalloids. In some parts of chemistry, such as the d-block and the f-block, horizontal similarities can be important as important as, or more pronounced than vertical similarities. Under an international naming convention, groups are numbered from 1 to 18 from the left most column to the right. A group or family is a vertical column in the periodic table. Groups usually have more significant periodic trends than periods and blocks, explained below. Modern quantum theories explain group trends by proposing that elements within the same group generally have the same electron shell configurations in the same shell. Consequently, elements in the group tend to have a clear trend in increasing atomic number with increasing number of electrons orbiting that nucleus.
For example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals. The asterisks in the above 18-column arrangement show where the repositioned f- block elements are to fit in the table. Reinstating them creates the 32-column form. The table here shows a widely used layout. Other forms show different structures in detail. Some questions remain as to the placement and categorisation of specific elements, future extensions and limits of the table, and whether there is an optimal form of table. The recognition of metals as solid, fusible and generally malleable substances dates from antiquity. Antoine Lavoisier may have been the first to formally distinguish between metals in 1789 with the publication of his’revolutionary’ Elementary Treatise on Chemistry. In America, they were known by the romanals, which were followed by an s-block if the group was in the s-most column or a p-block or a s-Block if they were in the p-Block. Metals are generally shiny, highly conducting solids that form alloys with one another. Nonmetals are colored or colorless insulating gases; nonmetALS that form compounds with othernonmetals feature covalent bonding. In between metals, which have intermediate or mixed properties. In between metal and nonMetals are meetingalloids, which has intermediate or Mixed properties.