Electron configuration is the term used to describe how the electrons in an atom are arranged on the shell(s) of the atomic orbital1. Each shell can hold a certain amount of electrons before moving onto the next shell. In the electron configuration, four letters are used as subshells to indicate how many electrons the shell can hold before moving onto the next one in the atomic orbital2. These four subshells are s, p, d and f.
The “s” subshell block is the first two left-sided column and the six columns on the far right side of the table are known as the “p” subshell block. The “d” subshell block is the middle ten columns and the “f” subshell block is the separated fourteen columns filled with the lanthanoids and the actinoids3. An electron configuration is displayed in this manner5:1s22s22p63s23p2 This is the electron configuration of the element, Silicon. The superscript, written as (x) in the configuration (e.g.
2s(x)) represents the number of electrons in the subshell.The first electron shell contains 2 electrons. The second electron shell is composed of the orbital shells “2s” and “2p”.
The “s” subshell can hold a maximum of 2 electrons while the “p” subshell can hold a maximum of 6 electrons. Together, they form the second electron shell, which can hold a maximum of 8 electrons before moving onto the next shell. On the Periodic table, elements are grouped according to a number of different factors. Some of the factors are:The number of orbital shells that are around the atom. For example: the descending order of the sixth column in the “p” block shows that Neon has two shells, Argon has three, Krypton has four shells4 and so forth… The increasing number of electrons in the shells. Going across the periodic table, we see that the atomic number increases. This number represents the number of electrons in the atom6 so therefore, Hydrogen is the first element in the periodic table because it has 1 electron and Oganesson is the last element because it has 118 electrons.
The finishing subshell. For example: Lithium is found in the “s” block because its electron configuration ends with “3s1”. Sulphur is in the “p” block because its electron configuration ends with “3p4” etc.