Difference Between Cation and Anion

Main Difference – Cation vs Anion

Cation and Anion are opposite terms in chemistry and stand for the two main types of ions formed. An ion is a state of matter upon the loss or gain of electron(s) compared to its actual state. When elements remain in their original form, they are known as ‘atoms’. However, most of the elements do not remain in their atomic state in nature; they tend to either acquire or giveaway electrons in order to attain stability like the noble gases. As a pre-step for the formation of compounds, these atoms transform them into positions or states of matter called ‘cations’ or ‘anions’. A cation is formed when an atom gives away electrons; an anion is formed when an atom acquires electrons. This is the main difference between cation and anion.

What is a Cation

As mentioned above, a cation is formed when an atom gives away electrons. The atomic nucleus consists of protons which are positively charged. An atom, in its original form, has an equal number of electrons and protons. Electrons are negatively charged and has a charge similar to that of a proton. Therefore, when an atom gives away electrons, it develops a relative positive charge, as the number of protons in the nucleus exceeds the number of electrons in the shell. Hence, cations are positively charged.

Cations are usually formed by metal atoms in an attempt to gain the noble gas configuration. The word cation in Greek means ‘down,’ which can be related to the lowering of the number of electrons. During the electrolysis processes, cations are attracted to the cathode as the cathode produces negative charges. Cations can be elemental or complex in nature. A cation complex will contain several elements grouped together which shares a positive charge. This is common among the d block elements. Furthermore, a single element can have several cations depending on their state of oxidation. i.e. singular charge, doubly charged, triply charged, etc. Some common cations include; Na⁺, Ca²⁺, Fe³⁺ etc.

What is an Anion

As mentioned in the introduction, an anion is formed when an atom acquires electrons. Therefore, due to the addition of these electrons, the number of electrons within the elemental shells exceeds the number of protons within the nucleus. As the protons are positively charged, and the electrons are negatively charged, the anion develops a negative charge.

Anions are usually formed by non-metal elements in an attempt to gain the noble gas configuration. The word anion in Greek means ‘up,’ which could be related to the increase in the number of electrons within the element. During the process of electrolysis, anions are attracted to the anode, as the anode produces positive charges. Anions can be elemental or complex in nature. An anion complex will contain several elements grouped together which shares the negative charge. This is common among the d block elements. Also, a single element can have several anions depending on their state of oxidation. i.e. singular charge, doubly charged, triply charged, etc. Some common cations include; F^–, O^2-, NO₃^– etc.