Periodic table

 The periodic table is a tabular arrangement of chemical elements organized based on their atomic numbers, electron configurations, and recurring chemical properties. It provides a systematic way of categorizing and understanding the elements that make up the known universe.

The modern periodic table consists of 118 confirmed elements, from hydrogen (H) with atomic number 1 to oganesson (Og) with atomic number 118. Elements in the periodic table are arranged in order of increasing atomic number from left to right and top to bottom. The table is divided into several blocks and periods.

The periodic table is divided into groups or columns, numbered from 1 to 18, and periods or rows, numbered from 1 to 7. Elements within the same group often exhibit similar chemical properties, while elements in the same period share similar electron shell configurations.

The elements in the periodic table are represented by their chemical symbols, typically one or two letters. For example, hydrogen is represented by H, carbon by C, and oxygen by O. Elements are also categorized into different blocks based on the subshells being filled with electrons. These blocks include s-block, p-block, d-block, and f-block.

Some notable groups in the periodic table include the alkali metals (Group 1), alkaline earth metals (Group 2), transition metals (Groups 3-12), halogens (Group 17), and noble gases (Group 18). Each group has its own unique characteristics and properties.

The periodic table is a fundamental tool in chemistry, as it helps scientists predict the chemical behavior and properties of elements based on their positions in the table. It allows for the classification and organization of elements, aiding in the study of chemical reactions, atomic structure, and the formation of compounds.