Elements in the same group have similar electron configurations from "summary" of The Periodic Table: A Very Short Introduction by Eric R. Scerri
The concept that elements in the same group have similar electron configurations is a fundamental principle of the periodic table. This means that elements within a group share certain common characteristics when it comes to the arrangement of their electrons. For example, all elements in Group 1 of the periodic table, also known as the alkali metals, have one electron in their outermost shell. This shared electronic configuration gives these elements similar chemical properties, such as their tendency to form positively charged ions by losing this single electron. Similarly, elements in Group 17, known as the halogens, have seven electrons in their outermost shell. This electron configuration makes these elements highly reactive, as they only need to gain one electron to achieve a full outer shell and attain a stable electron configuration. The reason why elements in the same group have similar electron configurations lies in the way the periodic table is structured. The periodic table is arranged in such a way that elements with similar chemical properties are grouped together. This organization is based on the number of electrons in the outermost shell of each element, which determines its chemical behavior. As one moves down a group in the periodic table, the number of electron shells increases, but the number of electrons in the outermost shell remains the same for elements within the same group. This is why elements in the same group exhibit similar chemical properties despite having more electron shells as one moves down the group.- The concept that elements in the same group have similar electron configurations is a key principle that helps us understand the periodic table and predict the properties of elements based on their position in the table. This concept provides a systematic way to organize the elements and make sense of their chemical behavior.
