What is an Ion?

You have been hearing since childhood that there are ions in our body, where some are positive and some negative. Positively charged ions are called cations, while a negative ion is known as an anion. 

An ion is an atom or a molecule that carries some charge either by losing or gaining an electron.

If we name the ions which are positively charged, then we have the following list:

  1. K+

  2. Na+

  3. Ca2+

  4. Mg2+

Negative ions are Cl-, O2-, S2-, Br-, etc.

This page will help you understand what is an ion with its types and the ion formation.

What Do You Mean by Ions?

Do you know what does ion mean and what type of ion forms when an atom loses electrons or what happens when an atom gains an electron?

An ion is a particle that possesses an electrical charge. It becomes a cation on losing an electron and becomes an anion when it gains an electron. Also, the negative charge or an electron an atom holds is always equal and opposite to the positive charge or protons of an atom.

What is a Charged Atom Called?

A charged atom is called an ion and what are ionic compounds made of; let’s understand this in detail:

What is an Ionic Compound? 

From the above text, we understood what an ion is in Chemistry. Now, we will understand what is an ionic compound. 

In Chemistry, we call ionic compounds chemical compounds that are formed of two or more ions held together by an electrostatic force of attraction; these electrostatic forces form bonds called ionic bonds. Here, these ionic bonds are formed between positively charged ions called cations and negatively charged ions called anions.

So, what is a cation? 

What is a Cation?

Now, Let’s Understand what is a Cation with a Real-Life Example:

What do you find common among the battery, your heart, and fertile soil? The answer to this question is, it requires cations to work.

However, let’s think more specifically. Have you ever gulped down a protein shake after becoming dehydrated from vigorous physical activity? Maybe a trainer, your coach, gym teacher, or even a sports drink commercial might have told you that consuming the beverage would help you replace your electrolytes. An electrolyte is a solution that contains ions and in drinking the sports drink, you consume cations. But what is a cation?              

A cation is a positively charged ion that gets attracted towards the cathode in electrolysis. As you know that an atom is electrically neutral. This is because the number of protons equals the number of electrons in an atom and the charges balance out. When an atom loses one or more electrons,  it now has more protons, or positively charged particles, than electrons, or negatively charged particles.

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What Type of Ion Forms When An Atom Loses Electrons?

For example, when atoms like Na, Ca, Mg, K loses electrons, it becomes positively charged by losing electrons accordingly:                                  

Atom

Net Charged Balanced 

Ion Formation

What Charge Does Ion Have?

23Na11

11 protons

11 electrons

Na - e-   →   Na+ 

11 protons

10 electrons


+1 net positive charge

38K19

19 protons

19 electrons

K  - e-   →  K+ 

19 protons

18 electrons


+1 net positive charge

24Mg12

12 protons

12 electrons

Mg - 2e-  →  Mg2+ 

12 protons

10 electrons


+2 positive charge

40Ca20

20 protons

20 electrons

Ca - 2e-   →   Ca2+   

20 protons

18 electrons


+2 positive charge


In the above, we can see that atoms on losing electron (s) become positively charged; however, the number of protons before and after the ion formation remains the same.

What is an Anion?

An anion carries a negative charge that gets attracted towards the anode in electrolysis. All non-metals gain two or more electrons and do not lose any proton. Therefore, these elements possess a net negative charge. Some examples of anions are Iodide ion (I- ), chlorine (Cl- ), hydroxide (OH-).

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Point To Ponder:

A trick to remember to distinguish between a cation and an anion is to say to yourself the following:

Cation -  'I positively love cats!', and

Anion -  ‘I get annoyed with negative people.’

What Type of Ion Forms When an Atom Gains Electrons?

Atom

Net Charged Balanced 

Ion Formation

What Charge Does Ion Have?

16O8

8 electrons

8 protons

O - 2e-   →   O2- 

8 protons

10 electrons


-2 net negative charge

14N7

7 electrons

7 protons

N + 3e-  → N3-  

7 protons

10 electrons


-3 net negative charge

18F9

9 electrons

9 protons

F + e-   →  F-

9 protons

10 electrons


-1 net negative charge

35Cl17

17 electrons

17 protons

Cl + e-   →   Cl-   

17 protons

18 electrons


-2 net negative charge


In the above table, we can see that non-metals like Cl, F, O, N when gains electron (s) becomes negatively charged or an anion with the increase in the number of electrons; however, the number of protons before and after the ion formation remains the same.

FAQs (Frequently Asked Questions)

Q1: What Happens When Ionic Compounds Dissolve in Water?

Ans: When ionic compounds dissolve in water, they break into individual ions; thereby leading to the process of dissociation. When the same ions are placed in water, the ions get attracted towards the water molecules, and therefore, each carries a polar charge.

Q2: How do You Make Chlorine (Cl) Safe to Eat?

Ans: Chlorine in its free form is detrimental to your health if you breathe the fumes or come in contact with the gas.  However, in reaction with sodium, it forms a compound called sodium chloride, as the sodium atom releases an electron to chlorine which accepts the electron to form the chloride anion. In this way, it becomes safe for you to consume Nacl or the common salt.

Q3: What Is H3O? Is H3O a Water Molecule?

Ans: H3O  is a Hydronium ion. It is another name for the aqueous cation H3O+, a kind of oxonium ion that is formed by the protonation of water. 


It is the positive ion that is produced when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in a solution release a proton (a positive hydrogen ion, H+). 


In simple words, it is formed by the combination of an H+ ion present in Arrhenius acid and water. It is different from water.