A negatively charged ion is known as ______.

Hint: Ions are the charged particles having either a positive charge or a negative charge. They gain the electrical charge by gaining or losing the electrons.

Complete answer:
In order to know about a negatively charged ion, let us first know about an ion.
What is an ion?
Ions are defined as the atoms or groups of atoms that have acquired an electrical charge by gaining or losing electrons.
For example:
Sodium ion ({ Na }^{ + }) has been created from the sodium atom after losing an electron.
$Na-{ e }^{ - }\rightarrow { Na }^{ + }$
Chloride ion $({ Cl }^{ - })$ has been generated from the chlorine atom after gaining an electron.
$Cl+{ e }^{ - }\rightarrow { Cl }^{ - }$
Ions are categorized into two types:
1. Cations: Cations are the positively charged ions and they have been created from the atoms by losing one or more electrons. (Example: ${ Na }^{ + }$)
2. Anions: Anions are the negatively charged ions and they have created from the atoms or groups of atoms by gaining one or more electrons. (Example: ${ Cl }^{ - }$)
Hence, the negatively charged ions are called anions.
It should be noted that depending upon how many electrons an atom or a group of atoms gain, anions can monovalent (an anion having single negative charge due to the loss of a single electron from its respective atom), divalent (an anion having two negative charges due to the loss of two electrons from its respective atom) and so on.
Negatively charged ions are termed anions because, in an electrochemical cell, anions are always attracted to the anode which is the positively charged electrode. From the name of the anode, the negatively charged ions are termed anions.
Similarly, in an electrochemical cell, positively charged ions, cations, are always attracted towards the cathode (negatively charged electrode).