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Shared electrons are shared equally between atoms only when two atoms of the same element form a covalent bond. Electrons are more attracted to the atom with the highest electronegativity when atoms of different elements share electrons through covalent bonds, resulting in polar covalent bonds.
Covalent compounds have lower melting and boiling temperatures than ionic compounds and are less likely to be soluble in water. Covalent compounds do not conduct heat and can be gaseous, liquid, or solid. The Lewis point structure of a molecule can help distinguish between different forms of covalent bonds. For each molecule, electron pairs have different names, depending on whether they share or not. A bonding pair is a pair of electrons that are shared between two atoms. A lone pair is a pair of electrons that are not shared by two atoms.
Covalent Bond
When atoms share electron pairs, this is known as covalent bonding. For higher stability, atoms will bond covalently with other atoms, which is accomplished by establishing complete electron shells. Atoms can fill their outer electron shells and achieve stability by sharing their outer (valence) electrons. Nonmetals easily make covalent bonds with other nonmetals for stability, and depending on the amount of valence electrons they have, they can form one to three covalent bonds with other nonmetals. Although atoms are believed to share electrons equally, when they form covalent bonds, but this is not always the case.
Octet Rule
To become stable, the octet rule states that all atoms in a molecule must have 8 valence electrons—shared, lost, or gained electrons. To comply with the octet rule, atoms in covalent bonds tend to share electrons. It takes 8 electrons to fill the s and p orbitals (electron configuration), often known as the noble gas configuration. Because noble gases have a charge of 0, every atom wants to be as stable as a noble gas. While it’s crucial to remember the “magic number” 8, keep in mind that the octet rule has several exceptions.
Example: Phosphorus has only 5 electrons in its outer shell (bold red). Argon has a total of 8 electrons, which satisfy the octet rule. Phosphorus must gain 3 electrons to follow the octet rule. It wanted to be like Argon, with a complete outer shell.
Single Bond
A single bond is when two electrons – an electron pair – are shared between two atoms. It is projected by a single line between two atoms. Although this form of bond is weaker and less dense than double and triple bonds, it is the most stable because it is less reactive, meaning electrons are lost for the benefit of atoms that want to steal electrons less likely.
Example: Hydrochloric acid
Double Bond
The phenomenon of two atoms sharing two pairs of electrons is known as a double bond. Two horizontal lines are drawn between two atoms in the molecule to represent it. This type of bond is much stronger than a single bond but less stable; this is because it is more reactive than a single bond.
Example: Carbon Dioxide
Triple Bond
When three pairs of electrons are shared between two atoms in a molecule, this phenomenon is called a triple bond. It is the least stable of the three common covalent bonds. It is very vulnerable to electronic thieves!
Example: Acetylene
Polar Covalent Bond
This covalent bond exists when the electronegativity of the bound atoms differs, resulting in an uneven distribution of electrons. Electrons are attracted to more electronegative atoms. The electronegativity difference of atoms is greater than zero but less than 2.
Non-Polar Covalent Bond
This type of covalent bond forms when two atoms share the same number of electrons. The electronegativity deficit between two atoms is zero.
Examples: Silicon dioxide, Methane, Carbon tetrachloride, Benzene
Coordinated or Coordinated Covalent Bonds
When one of the atoms in the bond shares electrons, this type of bond is formed. The reaction between ammonia with boron trifluoride achieves this. Boron has no electrons and nitrogen has two free electrons. By mixing nitrogen and boron, they were able to complete the final eight-electron shell.
Conclusion
A covalent bond is formed when the electrons of the two participating atoms are shared equally. The electron pairs participating in this bonding are called shared or bonding pairs. Another name for a covalent bond is molecular bond Shared bond pairs allow atoms to achieve stability in their outer shells, similar to noble gas atoms. Elements with extremely high ionisation energies cannot transfer electrons, and elements with extremely low electron affinity cannot absorb electrons. Atoms of these elements tend to share electrons with atoms of other elements or with atoms of the same element, allowing the two atoms to achieve an octet configuration in their respective valence shells, thereby achieving stability. A covalent bond refers to this bond formed by sharing pairs of electrons between different or similar types.
