Physical Science:

The periodic table of elements is a tabular arrangement of the chemical elements based on their atomic structure, chemical properties, and electron configurations. The modern periodic table consists of 118 elements and is arranged in rows and columns based on their atomic number and electron configurations. The periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers. This means that when elements are arranged in order of increasing atomic number, their properties exhibit a recurring or periodic pattern.

The discovery of the periodic table is generally attributed to the Russian chemist Dmitri Mendeleev, who published his version of the table in 1869. However, other scientists, including John Newlands and Julius Lothar Meyer, also made significant contributions to the development of the periodic table around the same time. Mendeleev’s table was particularly influential because he left gaps for undiscovered elements and predicted the properties of these elements based on their position in the table. When these elements were discovered, their properties were found to match Mendeleev’s predictions, which helped to establish the credibility of the periodic table Figure 8.2.1.

The modern periodic table is divided into two main categories: the "A" groups, also known as the main group elements, and the "B" groups, also known as the transition metals. The A groups, or main group elements, are located in columns 1, 2, and 13 to 18 of the periodic table. These elements are also known as the representative elements, and they are characterized by having valence electrons in the s and p orbitals of their outermost energy level. The A groups are further divided into two subcategories: the alkali metals (Group 1) and the alkaline earth metals (Group 2), which are located on the far left side of the periodic table, and the post-transition metals (Groups 13-16), the halogens (Group 17), and the noble gases (Group 18), which are located on the right side of the table. Rare earth elements (Group 3) are metallic chemical elements that are crucial components of many modern technologies, including smartphones, wind turbines, electric vehicles, and medical devices. These elements are similar in their electronic structure and chemical properties, and they all have partially filled 4f electron shells. Because the electronic properties of these elements are highly similar, they are difficult to separate, which is one reason why rare earth element extraction and refining can be challenging and expensive. Despite their name, rare earth elements are not actually rare. They are found in relatively small quantities in the Earth’s crust, and are often difficult and expensive to extract and refine.