What is the main difference between ionic and covalent bond?
Ionic Bond :
The bond formed by the complete transfer of electrons from one atom to another is called an ionic bond. Its also known as Electrovalent Bond.
FORMATION OF IONIC BOND:
Following are the conditions that are necessary for the formation of ionic bonds.
- One element should be metal while the other elements should be non–metal.
- The electronegativity difference between two bonded atoms should be 1.7 or Above
- The ionisation energy of metal should be low.
- The ionisation energy of non-metal should be high
Bond Formation In NaCl :
- Sodium belongs to group 1A
- Chlorine belongs to group 7A
- The electronegativity of sodium is 0.9.
- While the electronegativity of chlorine is 3.0
- The electronegative difference between Sodium (Na) and chlorine (Cl) is 2.1
- Hence, an Ionic bond is formed
- Sodium (Na) has one electron in its valance shell.
- So, sodium (Na) loses one electron to form sodium ion (Na+) and attain the electronic configuration of (Neon)
- Na -> Na + 1e
- Chlorine has seven electrons in its valance shell
- So it gains one electron to form chloride ions (Cl–) and attain the electronic configuration of argon
- Cl + 1e -> Cl
- The electrostatic force of attraction is established on Na+ and Cl-
- Therefore, crystal NaCl is formed.
Na+ + Cl– -> NaCl
BOND FORMATION IN CALCIUM CHLORIDE
- Ca belongs to group 2A
- Cl belongs to group 7A
- The electronegativity of calcium (Ca) is 1.0 ,while Chloride (Cl) is 3.0
- The electronegativity difference between Ca and Cl is 2.0
- Thus, an Ionic bond is formed.
- Calcium has 2 electrons in its outermost shell
- It tends to lose the electrons and attain the inert gas electronic configuration of Neon (Ne) and form Ca+2
Ca -> Ca+2 + 2e-
- Chlorine needs one electron to complete its outermost shell.
- It tends to gain one electron to attain the nearest noble gas electronic configuration.
- So it forms chloride ion (Cl-).
- 2Cl+ 2e– -> 2 Cl–
- Thus, the electrostatic force of attraction is established.
- Hence, white-coloured crystalline CaCl2 is formed.
Ca+2 + 2Cl -> CaCl2
The chemical bond formed by the mutual sharing of electrons between atoms is called a covalent bond.
FORMATION OF COVALENT BOND:
Both the elements should be non-metals.
The electronegativity difference between two bonded atoms should be less than 1.7.
FORMATION OF CL2:
- A chlorine molecule is formed from two chlorine atoms.
- The chlorine atom electronic configuration is ( 2,8,7)
- A chlorine atom has seven electrons in its valence shell.
- The two chlorine atoms mutually share one electron to form a chlorine molecule (Cl2).
- Therefore, both chlorine atoms attain the electronic configuration of argon(Ar) and complete their octet.
Cl + Cl -> Cl2
FORMATION OF CH4:
Carbon has four electrons in its valence shell and needs more 4 electrons to attain the noble gas (Ne) configuration.
Therefore, 4 atoms of hydrogen mutually share one electron each with a carbon atom to form a molecule of methane (CH4).
C + 4H -> CH4
Read -> Ionic bond
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