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Ionic and Covalent Compounds

Atoms are bonded together to form molecules. When two or more different chemically bonded with a fixed ratio, it is known as chemical compound. The expression that is used to express the ratio of elements present in a compound is called as chemical formula. For example, hydrogen and oxygen combine together in 2:1 ratio to form water. The chemical formula of water is H2O.

Chemical bonds are interaction between atoms to form a molecule. There are two types of chemical bonds; ionic and covalent bonds. Ionic bonds are formed through complete transfer of electrons between bonding atoms. For example; sodium loses one electron to form positively charged sodium ion and chlorine atom accepts one electron to form chloride ion with negative charge.

Now positively charged sodium ion and negatively charged chlorine ion will attract and attached together with an electrostatic force of attraction called as ionic bond. On the contrary, covalent bond is formed by equal sharing of electrons between bonding atoms.

For example; two chlorine atoms are bonded together to form chlorine molecule. In this case both atoms are bonded through equal sharing of electrons between atoms. Similarly oxygen molecule is also an example of covalent bond. Apart from these two bonds, there are metallic bonds, Van Der Wall bonds etc. In this article we will discuss about compounds with ionic and covalent bonds.

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What are Ionic and Covalent Compounds?

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The compounds with ionic bond are called as ionic compounds like sodium chloride. Similarly compounds like chlorine gas, oxygen gas are good examples of covalent compounds as they have covalent bonds between bonding atoms.

Electrostatic or electrovalent or ionic bond forms ionic compounds such as sodium chloride, magnesium chloride etc. whereas formation of four covalent bonds between one carbon atom and four hydrogen atoms forms methane molecule. Many of the compounds have ionic as well as covalent bonds such as sodium hydroxide (NaOH). 

Ionic Covalent Bond

Properties of Ionic and Covalent Compounds

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Since ionic compounds have ionic bonds which are electrostatic forces of attraction, they can decompose into respective ions. That is the reason; ionic compounds are ionic in nature and good conductor of electricity. They are usually found in solid state like sodium chloride etc. In ionic compounds, the constituent atoms or ions show strong attractions with other ions therefore they have high melting points, boiling points and found in solid state.

Due to presence of ions, ionic compounds are polar in nature and easily soluble in polar solvents like water. On the hands, they are insoluble in non-polar solvents like benzene, carbon tetrachloride etc. In case of covalent compounds, constituent atoms are bonded with covalent bonds (form through equal sharing of electrons). Therefore in covalent compounds, molecules are not very strongly attracted to other molecules results low boiling and melting points.

Difference Between Ionic and Covalent Compounds

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S.No Ionic Compounds Covalent Compounds
1Usually found in solid state ( Hard and crystalline)Usually found in gases, liquids, or solids
2Show high melting and boiling pointsShow low melting and boiling points
3Good conductor of electricitin molten and solutionPoor conductor of electricity in all phases
4Easily soluble in water but insoluble non-polar liquidEasily soluble in non-polar liquids but insoluble in waters
5Have ionic bonds between constituent atomsHave covalent bonds between atoms
6Enthalpies of fusion and vaporization is 10-100 times higher than covalent compoundsEnthalpies of fusion and vaporization is very less
7
This type of bonding is prevalent between nonmetal and metal
Example: NaCl , KCl
This type of bonding is prevalent between nonmetals
Example: CH4, Cl2, CO2

Similarities Between Ionic and Covalent Compounds

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Both ionic and covalent compounds are types of compounds. They can be differentiated easily due to different physical properties that are based on the nature of their bonding.  Similarity between them is that they are composed of their constituent atoms or ions. 

Some of the covalent compounds show similarity with ionic compounds such as graphite which is covalent in nature show electrical conductivity due to presence of free electrons. Similarly diamond is a hard solid like ionic compounds.

Naming Ionic and Covalent Compounds

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Let’s discuss naming and formula writing of ionic and covalent compounds. In case of ionic compounds, formula starts with cation followed by monoatomic or polyatomic anion. The subscripts are used to make neutral compound. For example; cation Na+ and anion Cl- will form NaCl.

Let’s discuss naming of binary ionic compound with a metal and a nonmetal.
  • In this naming, name the cation will come first, and then name of non-metal anion will be written with suffix (-ide).
  • For example name of NaCl would be to Sodium chloride, AlBr3 will be Aluminum bromide, SrI2 is Strontium iodide and so on.
  • Ionic compounds containing a metal and a polyatomic ion also follow same rule like Ca (NO3)2 is Calcium nitrate, (NH4)2SO4 is Ammonium sulfate, Mg (C2H3O2)2 is Magnesium acetate etc.
  • In binary covalent compounds with two non-metals, the number of elements with come as prefix like SO2 is sulphur dioxide, N2O is dinitrogen monoxide, N2O4 is dinitrogen tetroxide etc.
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