Explain why a carbon atom almost always forms four covalent bonds in a covalent substance. How is carbon monoxide an exception to this rule?

Short Answer

Expert verified
A carbon atom generally forms four covalent bonds due to its electronic configuration (1s²2s²2p²), with four electrons in its outer shell available for bonding. This allows it to fulfill the octet rule and achieve a stable electron configuration. Carbon monoxide is an exception, where carbon forms three bonds with oxygen (two covalent bonds and one coordinate covalent bond), still adhering to the octet rule and maintaining stability for both atoms.

Step by step solution

01

Electronic Configuration of a Carbon Atom

A carbon atom has six electrons, with the electronic configuration 1s²2s²2p². There are four electrons in the outer shell (two in the 2s subshell and two in the 2p subshell). These four electrons can participate in bonding, so a carbon atom can form four covalent bonds by sharing these electrons with other atoms.
02

The Octet Rule

The reason carbon and other non-metal atoms form covalent bonds is to achieve a more stable electron configuration. In general, atoms seek to achieve the electron configuration of the nearest noble gas, which adheres to the octet rule—where an atom has 8 electrons in its outer shell (except for helium, with only 2 electrons). By forming four covalent bonds, a carbon atom shares four electrons with other atoms, giving it a total of 8 electrons in its valence shell.
03

Carbon Monoxide as an Exception

Carbon monoxide (CO) is an exception to the rule of carbon forming four covalent bonds. In this molecule, carbon forms three bonds with oxygen instead of the usual four. The bonding in carbon monoxide involves two covalent bonds (single and double) between carbon and oxygen, as well as a coordinate covalent bond (also known as a dative bond), where the oxygen donates both electrons to the bond. This gives an electron configuration of 1s²2s²2p⁶ for carbon, fulfilling the octet rule for both the carbon and the oxygen.
04

Importance of CO Bonding

Carbon monoxide is an important exception to the typical rule of carbon forming four covalent bonds because it demonstrates that atoms can form different types of bonds to achieve a stable electron configuration. In the case of CO, the dative bond stabilizes the molecule and allows the carbon atom to still adhere to the octet rule, even though it only forms three bonds. In conclusion, a carbon atom typically forms four covalent bonds to fulfill the octet rule, creating a stable electron configuration. Carbon monoxide is an exception to this rule, as it forms two covalent bonds and one coordinate covalent bond with oxygen, still achieving a stable configuration for both atoms.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Study anywhere. Anytime. Across all devices.

Sign-up for free