Covalent Bonding and Covalent Compound Properties

Covalent Bonding

Introduction to Covalent Bonding

Covalent bonding is a fundamental concept in chemistry where atoms share valence electrons to achieve stable electron configurations. This type of bonding typically occurs between nonmetals.

• Valence Electrons: Electrons in the outermost shell of an atom that are involved in chemical bonding.

• Octet Rule: Atoms tend to share electrons to achieve a total of 8 valence electrons in their outer shell, similar to the electron configuration of noble gases.

• Duet Rule: Hydrogen atoms share electrons to achieve 2 valence electrons, filling their first shell.

Visualizing Covalent Bonding

The formation of covalent bonds can be illustrated using electron dot structures and energy level diagrams:

• Duet Rule Example: Two hydrogen atoms (H) share their single electrons to form H2, each achieving 2 electrons in their outer shell.

• Octet Rule Example: Two chlorine atoms (Cl) share one electron each to form Cl2, each achieving 8 electrons in their outer shell.

• Electron Dot Structures: These diagrams show shared pairs of electrons (as dots or lines) between atoms, representing covalent bonds.

Example: Which of these elements is likely to form covalent bonds? C (Carbon) is most likely, as it is a nonmetal and commonly forms covalent bonds.

Covalent Compound Properties

Physical and Chemical Properties of Covalent Compounds

Covalent compounds exhibit properties that are generally opposite to those of ionic compounds. These properties are important for understanding their behavior in different environments.

• Physical State: Covalent compounds are often found as gases, liquids, or solids at room temperature, but many are gases or liquids due to weak intermolecular forces.

• Electrical Conductivity: Covalent compounds are poor electrical conductors because they do not have free ions or electrons to carry charge.

• Melting and Boiling Points: Covalent compounds typically have low melting and boiling points compared to ionic compounds, due to weaker forces between molecules.

Property	Covalent Compounds	Ionic Compounds (for comparison)
Physical State	Gas, liquid, or solid (often gas/liquid)	Usually solid
Electrical Conductivity	Poor conductors	Good conductors when dissolved in water
Melting/Boiling Points	Low	High

Example: Water (H2O) is a covalent compound that is a poor conductor of electricity and has a relatively low boiling point compared to ionic compounds like sodium chloride (NaCl).

Additional info: Covalent bonding is essential for the structure and function of biological molecules, such as proteins, DNA, and carbohydrates, which are all composed of covalently bonded atoms.