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What are Ionic Compounds?

  • Last Updated : 21 Sep, 2021

In chemistry we usually come across terms called ions, anions, cations, ionic compounds study of such compounds is a must to understand various concepts. Let us understand why ions are formed generally, atoms are made up of particles called electrons, protons and neutrons. The number of electrons and protons are in the same number in any atom resulting in zero net charges. When an atom loses or gains electrons since electrons have a negative charge on them and protons have a positive charge and remains the same the net charge on the atom changes resulting in the formation of ions. When an atom loses its electrons a positive ion is formed whereas a negative ion is formed when it gains electrons. If a positive ion of one atom combines with the negative ion of another atom ionic compound is formed.

Ionic Compounds

Ionic Compounds can be defined as the chemical compound formed by opposite charged ions held together by ions bonds or electrostatic forces.

Ionic bonds are usually formed between a metal and non-metal. An atom always tends to get a stable electronic configuration when an atom loses electrons cation is formed and when an atom gains electrons anion is formed these two oppositely charged atoms attract together to form an ionic bond and the compound is called an Ionic Compound. 

Ionic compounds are held together by electrostatic forces since they are also called Ionic Compounds. Ionic Compounds are also formed when two atoms have a large electronegativity difference due to which one atom attracts electrons more than the other resulting in loss of electrons and gain of electrons in atoms.

Examples of Ionic Compounds

  • Sodium Chloride (NaCl)

Sodium has one electron in its valency shell to get a stable octet configuration sodium atom loses one electron since the number of protons doesn’t change and electrons decrease by one the net charge becomes +1 forming a cation. Whereas Chlorine has 7 electrons in its valency shell so it requires one electron to become stable it gains one electron from Sodium resulting in the formation of an Ionic Bond between Sodium and Chlorine forming NaCl.

  • Magnesium Chloride ( MgCl2)

Magnesium has two electrons in its valency shell to get a stable octet configuration Magnesium atom loses two electrons since the number of protons doesn’t change and electrons decrease by two the net charge becomes +2 forming a cation. Whereas Chlorine has 7 electrons in its valency shell so it requires one electron to become stable it gains one electron from Magnesium since Magnesium has lost two electrons and Chlorine can gain only one electron two Chlorine atoms combine together with one atom of Magnesium resulting in the formation of Ionic Bond between Magnesium and Chlorine forming MgCl2.

Properties of Ionic Compounds

  1. Crystalline in nature: Ionic compounds form crystalline structures however, it’s size depends on the size of anions and cations. The crystal structure of ionic compounds is uncharged since a number of cations are equal to anions that combine to form Ionic compounds.
  2. Hard and Brittle: Ionic compounds are hard since the ions are held together with strong electrostatic forces. These compounds are hard to break into pieces since they are held by strong forces so high pressure is applied to break so, ionic compounds brittle in nature.
  3. High melting and boiling points: Ionic compounds are hard and held by strong electrostatic forces making them hard to break. To break such strong forces and overcome the force of attraction between them high melting and boiling points are required. 
  4. High enthalpy of Fusion and Vaporization: Ionic compounds usually have higher enthalpies of Fusion and Vaporization than any other normal molecular compounds. Their enthalpies are 10-100 times greater than molecular compounds.
  5. Solubility: Ionic Compounds are soluble in polar solvents like water. They are less soluble in Non-Polar Covalent solvents.
  6. Good conductors of electricity in the aqueous or molten form: Ionic Compounds acts as a good conductor of electricity, when they are in aqueous or molten form because ionic compounds are closely packed which don’t allow any movement in ions thus making it a bad conductor of electricity but, when they are in aqueous or molten form ions are free to move which makes them good conductor of electricity in aqueous or molten form.
  7. Acts as insulators: Ionic Compounds act as good conductors of electricity when in a molten or aqueous form otherwise they act as insulators.

Difference between Ionic and Covalent Compounds

Following are the difference between Ionic and Covalent Compounds:

Ionic Compounds

Covalent Compounds

  • Ionic Compounds are formed by the transfer of electrons between atoms
  • Covalent Compounds are formed by sharing of electrons between atoms
  • Ionic bonds are stronger than covalent bonds
  • Covalent bonds are weaker when compared to ionic bonds
  • The atoms that combine together to form Ionic Compounds are charged
  • The atoms that combine together to form Covalent Compounds are electrically neutral
  • Ionic Compounds are formed by atoms of different elements
  • Covalent Compounds are formed by atoms of the same or other elements
  • Ionic Compounds occur in solid-state at room temperature
  • Covalent Compounds mostly occur in solid, liquid and gaseous state
  • These compounds are soluble in water
  • These compounds are not soluble in water
  • Ionic compounds conduct electricity in molten or aqueous form
  • Covalent Compounds do not conduct electricity in any form
  • Ionic Compounds have high melting and boiling points
  • Covalent compounds have fewer melting and boiling points when compared to ionic compounds
Examples: NaCl, MgCl2, NaOH etc.Examples: H2O, O2, Cl2 etc.

Sample Questions:

Question 1: Why do Ionic Compounds don’t conduct electricity in solid-state?

Answer: 

Ionic compounds conduct electricity due to the movement of electrons from one point to another point whereas in solid-state Ionic Compounds are strictly packed making the movement of ions impossible so, Ionic Compounds don’t conduct electricity in a solid state.

Question 2: Do Ionic Compounds

soluble in organic solvents?

Answer: 

Ionic compounds are not soluble in organic solvents like petrol and kerosene they are only soluble in polar covalent solvents like water.

Question 3: Mention the most common properties of Ionic Compounds?

Answer: 

Common properties that most Ionic Compounds share are:

  • Ionic compounds are crystalline in nature
  • They have high melting and boiling points
  • They are good conductors of electricity in molten and aqueous form
  • They are hard and brittle in nature

Question 4: Explain the term Ionic Compounds?

Answer: 

Ionic compounds are chemical compounds that are formed due to the transfer of electrons between oppositely charged ions that are held by electrostatic forces. These compounds are usually formed between metals and non-metals.

Question 5: Mention an Ionic Compound that is used daily for domestic purposes?

Answer: 

Ionic Compound that is most commonly used for domestic purposes is Sodium Chloride also known as Table Salt. If salt is observed in the magnifying glass a crystal structure can be seen also it is a bad conductor of electricity in the solid-state whereas it conducts electricity when dissolved in water.

Question 6: Which has the highest melting and boiling points MgO or NaCl?

Answer: 

Magnesium Oxide has higher melting and boiling points than sodium chloride. MgO has a melting point of around 2800 degrees celsius whereas NaCl has a melting point of around 801-degree celsius. This is because ionic bonding in Magnesium Oxide is stronger than Sodium Chloride due to the presence of more charges in Magnesium Oxide than in Sodium Chloride.

Question 7: Can Ionic Compounds act as electrolytes in solid-state?

Answer: 

No, Ionic Compounds cannot act as electrolytes in solid-state since they don’t conduct electricity they act as electrolytes in the aqueous or molten state because in order to act as conductor of electricity it involves movement of ions which is not possible in a solid-state.


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