H
Electron Dot Diagram
An electron is not an element.
The key to "happiness" for an atom is a full outer electron shell. (The outer electron shell is called the valence shell.) There are two conditions that cause a shell not to be full. Either it has only an electron or two (or three) in the outer electron shell or it's short an electron or two in that outer shell. The direct answer to the question is that if an element is chemically active, its outer electron shell is incomplete or is not full.
This is an ionic bond.
The electron
The element you are referring to is potassium. It has one electron in its outer shell and produces a faint purple color when excited.
Potassium has 1 electron in its outer energy level. When it forms a bond, it typically donates this electron to another element, leaving it with a full outer energy level.
Elements in Group 1 of the periodic table have one electron in their outer shell, while elements in Group 2 have two electrons in their outer shell. This configuration makes these elements more stable and likely to form ions with a positive charge by losing these outer electrons to achieve a full outer shell.
nobel gases has few electron in the outer energy level
It's outer valence electron shell(s).
The outer electron shells of halogens have seven electrons, making them one electron short of a full outer shell. This makes halogens highly reactive as they tend to gain an electron to achieve a stable electron configuration. Halogens are located in Group 17 of the periodic table.
Germanium is a group 14 element. It's electron structure is [Ar] 3d10 4s2 4p2. Therefore, it has 2 electron's in its outer shell.