Chemical Bonding - SS1 Chemistry Past Questions and Answers - page 4

Covalent bonding is a type of chemical bonding that occurs when two or more atoms share electrons in order to achieve a more stable electron configuration. Unlike ionic bonding, which involves the transfer of electrons, covalent bonding occurs between atoms with similar electronegativities. Covalent bonds are typically formed between nonmetallic elements. Let's explore the concept of covalent bonding and discuss the properties and characteristics of molecular compounds.

 

1. Covalent Bond Formation:

Covalent bonds are formed by the sharing of electron pairs between atoms. Each atom contributes one or more electrons to the shared pair, resulting in a bond that holds the atoms together. The shared electrons are attracted to both nuclei, creating a strong bond. Covalent bonds are often represented using Lewis structures, which depict the arrangement of atoms and their valence electrons.

 

1. Structure of Molecular Compounds:

Molecular compounds exist as discrete molecules, rather than an extended crystal lattice structure like ionic compounds. In a molecule, atoms are held together by covalent bonds, and the arrangement of atoms determines the molecular shape. Molecular compounds can range from simple diatomic molecules, such as oxygen (O2) and nitrogen (N2), to complex organic compounds like glucose (C6H12O6).

 

1. Physical Properties of Molecular Compounds:

Molecular compounds exhibit several characteristic properties:

-       Lower melting and boiling points: Compared to ionic compounds, molecular compounds typically have lower melting and boiling points. The intermolecular forces between molecules are weaker than the strong electrostatic forces in ionic compounds, resulting in lower energy requirements for phase changes.

-       Solubility: Molecular compounds can exhibit a wide range of solubilities in different solvents. The polarity of the compound and the solvent determines the solubility behaviour.

-       Electrical conductivity: Most molecular compounds do not conduct electricity in the solid or liquid state. Since covalent bonds involve the sharing of electrons, there are no free-moving ions to carry electric charge.

 

1. Chemical Properties of Molecular Compounds:

Molecular compounds participate in chemical reactions by breaking and forming covalent bonds. These reactions involve the rearrangement of atoms and sharing of electrons. Molecular compounds can undergo various types of chemical reactions, such as combustion, oxidation-reduction, and acid-base reactions. The reactivity of a molecular compound is influenced by factors such as bond strength, polarity, and the presence of functional groups.

 

Molecular compounds have diverse applications in fields such as pharmaceuticals, polymers, cosmetics, and agriculture. The ability to create specific molecular structures through covalent bonding allows scientists to design and synthesise compounds with desired properties and functions.