Covalent bonds

Definition

Covalent bonds are a type of chemical bond that involves the sharing of electron pairs between atoms. This bond is formed when two nonmetal atoms come together and share their valence electrons, resulting in a stable arrangement that lowers the overall energy of the system. Covalent bonds are critical in forming molecules and influence the properties of the substances they create, as well as how these substances interact with each other.

5 Must Know Facts For Your Next Test

1. Covalent bonds can be single, double, or triple, depending on how many pairs of electrons are shared between two atoms.
2. The strength of a covalent bond is influenced by the electronegativity of the atoms involved; greater differences in electronegativity can lead to more polar covalent bonds.
3. Covalent compounds typically have lower melting and boiling points compared to ionic compounds due to weaker intermolecular forces.
4. The sharing of electrons in covalent bonds allows for the formation of complex molecules, including organic compounds essential for life.
5. The concept of resonance explains how some molecules can be represented by multiple valid Lewis structures due to delocalized electrons in covalent bonds.

Review Questions

• How do covalent bonds differ from ionic bonds in terms of electron interactions and properties of compounds?
  • Covalent bonds involve the sharing of electron pairs between nonmetal atoms, while ionic bonds result from the transfer of electrons from one atom to another, typically between metals and nonmetals. Compounds formed by covalent bonds often exhibit lower melting and boiling points compared to ionic compounds because the forces holding covalent molecules together are generally weaker. Additionally, covalent compounds can be gases or liquids at room temperature, whereas ionic compounds are usually solid crystals.
• Discuss how electronegativity affects the type of covalent bond formed between two atoms.
  • Electronegativity is a measure of an atom's ability to attract shared electrons in a bond. When two atoms with similar electronegativities form a bond, they tend to share electrons equally, resulting in a nonpolar covalent bond. If there is a significant difference in electronegativity between the two atoms, the electrons will be shared unequally, leading to a polar covalent bond. This unequal sharing results in partial charges on the atoms and influences the molecule's overall polarity and reactivity.
• Evaluate how molecular geometry influences the properties and reactivity of covalent compounds.
  • Molecular geometry is determined by the arrangement of atoms and the type of covalent bonds present within a molecule. The shape affects physical properties such as polarity, boiling and melting points, and solubility. For instance, a bent shape caused by polar covalent bonds can lead to a molecule being polar overall, which influences its solubility in water. Furthermore, geometry plays a crucial role in how molecules interact with each other during chemical reactions, determining reactivity patterns and product formation.

Related terms

valence electrons: Electrons in the outermost shell of an atom that are involved in forming bonds with other atoms.

polar covalent bond: A type of covalent bond where the electrons are shared unequally between the two atoms, leading to a slight electrical charge on each atom.

molecular geometry: The three-dimensional arrangement of atoms in a molecule, which is influenced by the presence and type of covalent bonds.