Anion or Cation: How to Differentiate Them?
Anions and cations are ions with a positive or negative ionic charge that give them their own characteristics.


To understand anions and cations, it is important to know what an ion is. Ions are molecules with an electrical charge caused by an odd number of protons and electrons. When a molecule has no electric charge, which means that it has the same number of electrons as protons, it is called a neutral atom.



Protons are very stable subatomic particles that are found in the nucleus of molecules. They have a positive charge and are, for the most part, accompanied by neutrons. Moreover, it is the number of protons in the nucleus of an element that defines its atomic number and its position in the periodic table.



These stable subatomic particles are also found near the nucleus, they will, however, orbit around it. The electrons have a negative charge and have a mass representing 1 / 1836 of that of the proton; this is why electrons are not counted in the atomic mass of elements.


The Anions

They are ionized molecules of negative charge. This means that they have a greater number of electrons than protons. In general, the electrons gained come from surrounding molecules with less affinity, often caused by their categorization as nucleophiles or electrophiles.

Among the most common anions are chloride (Cl-), bromide (Br-) and sulfate (SO42-)


The cations

Unlike anions, cations are positively charged atoms due to the loss of an electron. This means that the number of protons is greater than the number of electrons.

Among the most common cations are sodium (Na+) and iron (Fe2+).



  • A little tricks to remember the electrical charge of anions and cations. The anion has an "N" for the negative. A cation has a "t", which looks like a "+" for positive.




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What is Osmotic Pressure?
It is the pressure that must be applied on the solution side to stop the movement of the fluid when a semipermeable membrane separates the two mixtures.