According to the Copenhagen interpretation of quantum mechanics, the position of a particular electron is not well defined until an act of measurement causes it to be detected.

Electron configurations:

Electron configurations are one way to show e⁻ distribution in atoms.

An electron configuration consists of a number and letter, representing the occupied subshell, followed by a superscript indicating the number of electrons in the subshell.

The electron configuration for sodium (atomic number 11) is:

1s²2s²2p⁶3s¹

• The large numbers represent the energy level.
   
• The letters represent the sublevel.
   
• The superscripts indicate the number of electrons in the sublevel.