Halogens always form anions, alkali metals and alkaline earth metals always form cations. Most other metals form cations (e.g. iron, silver, nickel), whilst most other nonmetals typically form anions (e.g. oxygen, carbon, sulfur).
How do you know which element will form a cation?
You can often determine the charge an ion normally has by the element's position on the periodic table:
- The alkali metals (the IA elements) lose a single electron to form a cation with a 1+ charge.
- The alkaline earth metals (IIA elements) lose two electrons to form a 2+ cation.
What type of elements form cations and why?
Cations can be formed from metal elements, as well as nonmetal elements. If a metal element forms an ion, it always forms a cation. ... For example, sodium always forms a +1 cation and magnesium always forms a +2 cation. Some metals are flexible and can form more than one type of cation.
