Note the difference between an ion and anion.
We all very well know about the importance of grammar in English. In any language, grammar plays an important role and it is useful to convey the message correctly. Punctuation is also to be followed correctly to get the sentence's correct meaning. Even a space between two words will also alter the meaning.An ion is a charged particle as per the science we all studied. The charge may be either positive or negative. Anion is a negatively charged particle. so the space between an ion will change the meaning a lot.
As an example, we can take a sentence. Ammonium is an ion. This conveys the correct meaning. But we write the same as ammonium is anion, it conveys a wrong meaning. As ammonium is a positively charged particle ( Cation) saying ammonium is anion is not correct.
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