Covalent bond

Definition

A covalent bond is a type of chemical bond where two atoms share one or more pairs of electrons, allowing each atom to attain a stable electron configuration similar to that of noble gases. This sharing of electrons leads to the formation of molecules and is fundamental in the study of molecular compounds. Covalent bonds can vary in strength and length, depending on the number of shared electron pairs and the types of atoms involved.

5 Must Know Facts For Your Next Test

1. Covalent bonds can be single, double, or triple, depending on whether one, two, or three pairs of electrons are shared between the atoms.
2. The strength of a covalent bond is influenced by factors such as atomic size and the electronegativity of the bonded atoms.
3. Covalent bonds result in the formation of distinct molecular geometries due to the arrangement of shared electron pairs around the bonded atoms.
4. In a molecule with polar covalent bonds, the overall molecular polarity is determined by the shape and arrangement of the polar bonds.
5. Covalent bonding is essential for life as it forms the backbone of organic molecules like proteins, nucleic acids, and carbohydrates.

Review Questions

• How does the sharing of electrons in a covalent bond differ from the transfer of electrons in an ionic bond?
  • In a covalent bond, two atoms share electrons to achieve stability, while in an ionic bond, one atom donates electrons to another, resulting in the formation of charged ions. This fundamental difference in electron interaction leads to distinct properties for covalently bonded compounds and ionic compounds. Covalent bonding typically results in the formation of discrete molecules with specific geometries, whereas ionic bonding results in a lattice structure.
• Evaluate how electronegativity differences influence whether a bond is classified as covalent, polar covalent, or ionic.
  • Electronegativity measures an atom's ability to attract electrons. When two atoms have similar electronegativities (typically less than 0.4 difference), they form nonpolar covalent bonds by sharing electrons equally. If there's a moderate difference (0.4 to 1.7), a polar covalent bond forms where electrons are shared unequally. If the difference is greater than 1.7, one atom pulls electrons away completely, resulting in an ionic bond. Thus, electronegativity differences play a critical role in determining bond type.
• Assess how molecular geometry influences the physical properties of compounds formed by covalent bonds.
  • Molecular geometry significantly impacts physical properties such as boiling points, solubility, and reactivity of covalently bonded compounds. The shape of a molecule determines how it interacts with other molecules and influences its polarity. For instance, polar molecules often have higher boiling points due to dipole-dipole interactions compared to nonpolar molecules that may have London dispersion forces. Understanding molecular geometry is crucial for predicting behavior and reactivity in chemical reactions involving covalent compounds.

Related terms

polar covalent bond: A polar covalent bond occurs when two atoms share electrons unequally due to differences in their electronegativity, resulting in a partial positive charge on one atom and a partial negative charge on the other.

nonpolar covalent bond: A nonpolar covalent bond is formed when two identical atoms share electrons equally, leading to no charge separation across the bond.

molecular compound: A molecular compound consists of molecules formed by covalent bonds between two or more nonmetal atoms, typically having distinct properties from ionic compounds.