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Types of Compound and their Properties

Grade 9
Aug 22, 2022

Key Concepts

• Chemical bond

• Ionic bond

• Covalent bond

• Molecule

• Molecular bond


Types of Compounds


A compound is a pure substance made up of two or more kinds of elements that are chemically combined. When they combine, the atoms of one element make connections with the atoms of another element in very specific ways. 

By combining in compounds, elements can form more complex substances. Compounds form through chemical bonds, which are links between two or more atoms that hold the atoms together. The molecules that make up compounds range from small to large. For example, sugar is the energy source for living things. Sugar or glucose is a molecular compound made up of molecules. Each molecule contains 24 atoms.  

glucose structure

The table salt is a molecule of two different atoms called sodium and chlorine. The structure of the table salt is a crystal lattice. In three-dimensional, the structure of the table salt is as below. 

nacl structure


The electrons move around the nucleus. Nucleus contains protons that are positively charged particles and the electrons are the negatively charged particles. The attractive force between the electrons and the protons in an element depends on the structure and the number of electrons and protons. Based on it, some elements are unstable as the nucleus cannot hold the electrons around them. They try to move to the other element forming a compound. This is called bonding. These bonds are chemical bonds. 

Covalent bonding:  

The bonding of elements is done by sharing an electron. One element shares one of the electrons with another element. The shared electron travels in both the elements and makes the compound stable.  


The compounds formed through this manner are called covalent compounds. In a covalent bond the electron is shared between the two elements. The covalent bond is of different types. They are single covalent bond, double covalent bond and triple covalent bond. If we see two covalent bonds in a single compound, then we say that the compound is of double covalent bond. 

Properties of Covalent compounds: 

These compounds can be either solid, or liquid, or gas at room temperature. Usually, covalent compounds have the least boiling and melting points compared to the ionic compounds. The atoms in covalent compounds do dissolve in the water as the ionic compounds do. The solution of the covalent compounds does not conduct the electricity and act as insulators. 

types of covalent bonds

Carbon dioxide and water are the two simple and best examples for covalent bonds. The water molecule contains two hydrogen elements and an oxygen element, and the carbon dioxide contains two oxygen elements and a carbon element. Let us assume a jar full of water. The jar contains millions, billions or maybe trillions of water molecules in it. The compounds move randomly and hit one to the other, but the atoms in one water molecule does not bond with the other water molecule. 

Ionic bonding:  

The bonding of elements if done by one element giving away its electron to gain the stability to the other element is called the ionic bond. The compound formed through the giving away of the electron is called an ionic compound. The ionic bond occurs between the elements that are short of an electron for stability and another element that is excess of electron.  

ionic bonds

Properties of Ionic compounds:  

These compounds are usually solid at a room temperature. They can easily break apart. They have high melting and boiling points. The ionic compounds that dissolve in water are good conductors of electricity. The charges of the ions and the forces that hold them together in the compound are responsible for these properties of ionic compounds. 

Ionic compounds exist as a solid in the form of an ionic lattice. An ionic lattice is a repeating pattern of positive and negative ions. In an ionic compound, all the positive ions attract all the negative ions everywhere in the same crystal. 

Fig 1

Characteristics of ionic and covalent bond: 

ionic bond vs covalent bond


• Atoms are the basic unit of any matter around us.

• Two or more elements combined together are called compounds.

• The formation of the compounds is for the stability of the compound.

• The bonding of elements is called chemical bonds.

1. Ionic bond

2. Covalent bond

• Ionic bond is formed by transferring electrons from one atom to the other atom.

• Covalent bond is formed by sharing the electron from one atom between two atoms.


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