Electronic Configuration and the Periodic Table a Study

Electronic configuration and the periodic table a study

At first glance, the periodic table -- that chart that appears on the walls of science classrooms everywhere -- appears to be an oddly shaped collection of chemical information about the elements. A closer look, however, reveals the source of the table's name: The elements are arranged "periodically;" that is, according to properties that repeat in regular, predictable patterns. This periodic arrangement of the elements makes the table very useful, in that if you know the location of an element in the table, you can predict its properties.

The more than 100 elements that make up the periodic table are organized in a series of 18 columns and 7 rows. Each column is called a group, or family. Each row is called a period. Elements in the same group have similar physical characteristics. For example, all of the elements in group 1 (at the far left) react easily with other elements. Unlike the elements in a group, however, the elements in a period do not share properties. Rather, the properties of the elements change as you move from left to right across the row. But to understand why the table is organized as it is, it's helpful to understand the structure of atoms.

An atom is the smallest particle of an element. An atom of any given element is made up of a certain number of protons, an equal number of electrons, and approximately the same number of neutrons. (The exception is hydrogen, which can have zero neutrons.) Protons and neutrons form the nucleus of an atom, and electrons swarm around the nucleus. This swarming isn't completely haphazard, though. Electrons inhabit various energy levels, or shells. The electron configuration shown in the periodic table indicates how many electrons are found in each shell, from innermost to outermost. For example, the electron configuration for calcium is 2,8,8,2.

Electron configuration depends upon the energy state and magnetic spin of each electron, and these...