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Question
What is an ion ? How is an ion formed ? Explain with the help of two examples of different ions.
Solution
An ion is an electrically-charged atom or molecule in which the total number of electrons is not equal to the total number of protons.
An ion is formed when a neutral atom loses or gains electrons. This loss or gain of electrons imparts a charge (positive or negative) to the neutral atom making it an ion.
There are two different types of ions:
If a neutral atom loses an electron, an overall positive charge is imparted to the atom and it becomes a positively-charged ion. A positively charged ion is called a cation. In a cation, the total number of electrons is less than the total number of protons as compared to the neutral atom. For example, sodium readily loses an electron to become a positively-charged sodium ion (Na+).
If a neutral atom gains an electron, an overall negative charge is imparted to the atom and it becomes a negatively-charged ion. A negatively-charged ion is called an anion. It has more no of electrons than the number of protons compared to the neutral atom. For example, chlorine readily gains an electron to become a negatively-charged chloride ion (Cl-).
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RELATED QUESTIONS
What are polyatomic ions? Give examples.
Write the symbols and valencies of the following radicals:
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State whether the following statements are true or false :
A chloride ion has negative charge because it has more electrons than a neutral atom.
Fill in the following blank with suitable word:
The particle which is formed by the loss or gain of electrons by an atom is called..............
Fill in the following blank with suitable word:
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Explain the formation of (i) sodium ion, and (ii) chloride ion, from their respective atoms giving the number of protons and number of electrons in each one of them. What is the reason for positive charge on a sodium ion and a negative charge on a chloride ion ?
Give example.
Bivalent acidic radicals
Match the radicals in List I with their correct names from List II.
| List I | List II | |
| 1. `"NO"_3^(1-)` | A: Bisulphite | F: Sulphate |
| 2. `"HSO"_4^(1-)` | B: Phosphate | G: Nitrate |
| 3. `"SO"_4^(2-)` | C: Carbonate | H: Phosphite |
| 4. `"PO"_4^(3-)` | D: Nitrite | I: Sulpite |
| 5. `"HCO"_3^(1-)` | E: Bicarbonate | J: Bisulphate |
State if the following element or radical is divalent?
Sulphite
State if the following element or radical is divalent?
Bisulphite
