The periodic table of elements is a tabular arrangement of the chemical elements, organized on the basis of their atomic number, electron configurations, and chemical properties. The elements are arranged in rows and columns according to their atomic number, which is the number of protons in the nucleus of an atom of that element. The elements are also grouped into families or groups, which have similar chemical and physical properties.
The modern periodic table was first proposed by Russian chemist Dmitry Mendeleev in 1869, who recognized that the elements had a repeating pattern of properties, which he called the “periodic law.” Mendeleev’s table had gaps, which he left open for the discovery of new elements. Today, the periodic table has 118 known elements, with the most recent addition being elements 113, 115, 117 and 118 which were discovered in recent years.
Each element in the periodic table is represented by a unique symbol, which is usually a one- or two-letter abbreviation of the element’s name. For example, the symbol for hydrogen is “H,” and the symbol for gold is “Au.” The element’s atomic number, symbol, and weight are usually listed on the top of each element box.
The elements are organized into rows and columns in the periodic table. The rows are called periods, and the columns are called groups or families. The elements in a group have similar chemical and physical properties. For example, the elements in Group 1 (also known as the alkali metals) are all highly reactive, while the elements in Group 18 (also known as the noble gases) are all non-reactive.
The elements in a period have similar electron configurations, but they have different chemical properties. For example, the first period has the elements hydrogen, helium, lithium, beryllium, and boron, which have one, two, three, four, and five electrons in their outermost energy level, respectively. The elements in the first period have very different chemical properties, with hydrogen being a gas, helium an inert gas, lithium being a metal and so on.
The periodic table also has several special rows called transition elements, inner transition elements and lanthanoids and actinoids. Transition elements have unique electronic configuration and are present in the middle of the table, mostly in the d-block. They are known for having unique chemical properties and are used extensively in industry and daily life. Inner transition elements are present in the f-block and have unique electronic configuration. Lanthanoids and actinoids are unique set of elements present at the bottom of the table, known for their unique electronic configuration and radioactive properties.
In conclusion, the periodic table is a powerful tool for organizing and understanding the properties of the elements. It is a fundamental tool used in chemistry, physics, and many other sciences. The elements are arranged in rows and columns according to their atomic number, electron configurations, and chemical properties, allowing for easy identification and prediction of properties for new elements. The table also has many special rows for unique set of elements, known for their unique electronic configuration and properties.