Question

In a covalent bond formation, (a) transfer of electrons takes place (b) equal tharing of electrons between two atoms takes place (c) electrons are shared by one atom only (d) electrons are donated by one atom and shared by both atoms.

Short answer

The correct answer is (b) equal sharing of electrons between two atoms takes place.

Step-by-step solution

Understanding Covalent Bonds

A covalent bond is a type of chemical bond where two atoms share one or more pairs of electrons. The atoms tend to share electrons in such a way that they can achieve a stable electronic configuration, akin to that of noble gases.

Analyzing the Options

Analyze each given option to determine if it correctly describes a covalent bond. (a) Involves transfer of electrons, which is characteristic of ionic bonds, not covalent. (b) Talks about equal sharing of electrons between two atoms, which is a property of covalent bonds. (c) Indicates only one atom shares electrons, which does not describe covalent bonds accurately. (d) Suggests one atom donates electrons for sharing, which again does not correspond to covalent bond formation.

Selecting the Correct Option

Based on the definition and properties of covalent bonds, where electrons are shared between two atoms, option (b) 'equal sharing of electrons between two atoms' is the correct description of covalent bond formation.

Key concepts

Chemical Bonds

Chemical bonds form the backbone of molecular structure, dictating the stability and behaviors of compounds. They are essentially the forces that hold atoms together within a molecule.

There are three main types of chemical bonds: ionic, covalent, and metallic. Ionic bonds occur when electrons are transferred from one atom to another, leading to the formation of charged ions that attract each other. Covalent bonds, on the other hand, involve the sharing of electron pairs between atoms. Metallic bonds are characterized by a 'sea' of electrons that are free to move around, which gives metals their distinctive properties.

These bonds enable atoms to achieve more stable configurations, typically by filling their outer electron shells. The type of bond formed between atoms greatly influences the properties of the resultant molecule, such as melting and boiling points, electrical conductivity, and solubility.

Sharing of Electrons

The sharing of electrons is the defining feature of covalent bonds, differentiating them from other bond types. In a covalent bond, two atoms pool their valence electrons, essentially 'taking turns' using them to achieve filled outer shells, or a more stable state.

These shared electrons create an attractive force, gluing the atoms together within the molecule. Covalent bonds can involve the sharing of one, two, or even three pairs of electrons, known as single, double, and triple bonds, respectively. The covalent bonds' strength is contingent on the number of shared electron pairs, with more pairs equating to stronger bonds.

It's important to note that the sharing isn't always equal – it can vary depending on the electronegativity of the atoms involved. Atoms with closer electronegativity values tend to share electrons more equally, as seen in many organic compounds like methane (CH4). In contrast, atoms with differing electronegativities may share electrons unequally, leading to polar covalent bonds, as in water (H2O).

Stable Electronic Configuration

Atoms naturally gravitate toward the most stable electronic configuration, often mimicking the electron configuration of the nearest noble gas. This pursuit of stability underpins the formation of chemical bonds.

The noble gases have full valence shells, which makes them unusually unreactive compared to other elements. Other atoms engage in bond formation to achieve a similar state of fullness in their outer shells, a condition known as the octet rule for most elements. This rule indicates that atoms tend to form bonds until they have eight electrons in their valence shell, which is regarded as a particularly stable arrangement.

In covalent bonding, atoms share their valence electrons with other atoms to complete their outer shell. For example, two oxygen atoms share two pairs of electrons to form O2, each thereby achieving the stable electronic configuration of Neon. This sharing allows both atoms to 'feel' like they have full outer shells, optimizing their stability and reactivity – a concept that greatly simplifies the complex dance of electrons that characterizes chemical interactions.