Sodium and chlorine are the best examples to illustrate how elements form compounds.
Notice how sodium is just one electron more from being stable? and that chlorine is just one electron less from being stable?
Look below and see that when sodium and chlorine atoms bump together, their outer orbits' electron will react with each other.
The positive chlorine nucleus is stronger, so, it is able to pull the loosely held sodium electron into it's orbits.
The transfer of an electron from the metallic sodium to a non-metallic chlorine rewulted in a new structure for both atoms. Sodium has given up one electron, and chlorine accepted it. Now, the arrangement of the atoms are stable, but it no longer has a structure of a neutral atom.
The movement of an electron from one atom to another is called electron transfer. This results in the formation of charged particles named ions. Ionic compound are formed from the bond that occurs between a positive ion, which are called cation, and a negative ion, known as anions. Both the Na and Cl particles are ions, because they each have an electrical charge. They are attracted to each other because of their opposite charges. This force of attraction between + and - ions is called an ionic bond. If an atoms gains electrons, it has a negative charge and tends to be non-metal. However, if an atom loses electrons, it has a positive charge and are usually metallic. It is the attraction between positive sodium ions (Na+1) and negative chloride ions (Cl-1) that holds the new compound together! Therefore, Sodium chloride is called an ionic compound, because it is made up of ions and held together by ionic bonds.
| Element Name | Atom Symbol | Ion Symbol | Ion Name | Type of Ion | |
|---|---|---|---|---|---|
| Sodium | Na | Na+1 | Sodium | cation | |
| Chlorine | Cl | Cl-1 | Chloride | anion |
Members of the halogen family form ions with a charge of -1 because they need to take on one electron to complete their outer orbit. Alkali metals form ions with a charge of +1 as they tend to lose one negative electron to form a neutral atom.
