Difference Between Anion and Cation

Anion vs Cation

Commonly, anions and cations are called ions. The atoms of various elements are not stable (except the noble gases) under normal conditions. To become stable, they undergo various chemical changes especially regarding the number of electrons. For example, they can remove or gain electrons or else share electrons in order to gain the stable electron configuration. When this is happening, elements tend to join with other elements. Chemical elements can join with each other to form chemical compounds. The elements are bonded together by chemical bonds, which have ionic or covalent characteristics. If the compounds have ionic bonds, they are known as ionic compounds. Ionic compounds are formed by the attraction between positive and negative ions. Ions are charged species. Therefore, they are attracted to electric fields, and when moving, their path is deflected by a magnetic field. Ions are also responsible for conducting electricity through solutions or liquids.


Anions are the negatively charged ions formed by neutral atoms. When an atom attracts one or more electrons to its outer orbital, negative ions are formed. In a neutral atom, the number of electrons in the outer shells is equal to the number of protons in the nucleus. Electrons are negatively charged, and protons are positively charged. Since the numbers are equal, the atoms have no charge. However, when an atom attracts more electrons from outside, the number of electrons increases, thus the atom becomes negatively charged. In order to attract electrons, there should be some other species, which readily gives electrons to anionic atoms. According to the number of electrons gained, the charge size varies. For example, if a one electron is obtained a monovalent anion forms and if two electrons are obtained divalent anions form. Normally, anions are formed by non-metals elements, which are in the p block of the periodic table. For example, nitrogen forms a -3 anion, oxygen forms a -2 anion and chlorine forms a -1 anion. These atoms are more electronegative, hence has the capability to attract electrons and form anions.

Not only single atoms, but there can be several atoms or molecules forming anions. If the anion is only an atom, it is known as monoatomic anion. If the anion has several atoms, or if it is a molecule, it is known as polyatomic anion. Anions are attracted to the positively charged electric fields or any positively charged species.


Cations are positively charged ions. Cations form when a neutral atom removes one or more electrons. When they remove electrons, the number of protons in the nuclei is higher than the number of electrons in outer shells; hence, the atom gets a positive charge. Cations are formed by metals in s block, transition metals, lanthanides and actinides, etc. Like the anions, cations can also have various charge sizes depending on the number of electrons removed. Therefore, they form monovalent (Na+), divalent (Ca2+), and trivalent (Al3+) cations. In addition, there can be monoatomic cations and polyatomic cations (NH4+). 


What is the difference between Anion and Cation?

• Anions are negatively charged, and cations are positively charged.

• Anions form by attracting electrons and cations form by removing electrons.

• Anions are mainly made by non metals where as cations are made by metals.

• Anions attract to positive ends of an electric field, whereas, cations are attracted to negative ends.