Question

The nature of bonding in ${\mathrm{CCl}}_4$ and ${\mathrm{CaH}}_2$ is (1) electrovalent in both ${\mathrm{CCl}}_4$ and ${\mathrm{CaH}}_2$ (2) covalent in ${\mathrm{CCl}}_4$ and electrovalent in ${\mathrm{CaH}}_2$ (3) electrovalent in ${\mathrm{CCl}}_4$ and covalent in ${\mathrm{CaH}}_2$ (4) covalent in both ${\mathrm{CCl}}_4$ and ${\mathrm{CaH}}_2$

Short answer

(2) Covalent in ${\text{CCl}}_4$ and electrovalent in ${\text{CaH}}_2$.

Step-by-step solution

Understand the Types of Bonding

There are two main types of bonding: electrovalent (also called ionic) and covalent. Electrovalent bonding occurs when electrons are transferred from one atom to another, usually between a metal and a non-metal, resulting in the formation of ions. Covalent bonding, on the other hand, occurs when two atoms share electrons, typically between non-metals.

Analyze Bonding in ${\text{CCl}}_4$

${\text{CCl}}_4$ (carbon tetrachloride) is composed of carbon (a non-metal) and chlorine (also a non-metal). The carbon atom shares electrons with four chlorine atoms, forming covalent bonds. Therefore, the nature of bonding in ${\text{CCl}}_4$ is covalent.

Analyze Bonding in ${\text{CaH}}_2$

${\text{CaH}}_2$ (calcium hydride) consists of calcium (a metal) and hydrogen (a non-metal). Calcium loses two electrons to form ${\text{Ca}}^{2+}$ ions, and each hydrogen gains one electron to form ${\text{H}}^{-}$ ions. This transfer of electrons results in electrovalent (ionic) bonding in ${\text{CaH}}_2$.

Determine the Correct Answer

Given that ${\text{CCl}}_4$ has covalent bonds and ${\text{CaH}}_2$ has electrovalent bonds, the correct answer is: (2) covalent in ${\text{CCl}}_4$ and electrovalent in ${\text{CaH}}_2$.

Key concepts

Covalent Bonding

Covalent bonding is one of the fundamental types of chemical bonding. It occurs when two atoms share a pair of electrons. This type of bonding usually takes place between non-metal atoms. The shared electrons help each atom achieve a stable electron configuration, similar to that of noble gases. The shared electrons are counted as part of each atom's valence shell, completing the shell and making the atom more stable.

Here are some key characteristics:

• Occurs between non-metals
• Involves sharing of electron pairs
• Creates molecules with stable structures

Understanding covalent bonds is crucial because they form the basis of many substances important to life, such as water, oxygen, and various organic compounds.

Ionic Bonding

Ionic bonding, also known as electrovalent bonding, happens when electrons are transferred from one atom to another. This process typically occurs between metals and non-metals. Metals tend to lose electrons, forming positively charged ions, while non-metals gain electrons, forming negatively charged ions. The opposite charges attract each other, creating a strong electrostatic force that holds the ions together.

Key points about ionic bonding include:

• Occurs between a metal and a non-metal
• Involves transfer of electrons
• Formation of positive and negative ions
• Results in the formation of ionic compounds, such as salts

Ionic bonding is responsible for the high melting and boiling points of ionic compounds, and their ability to conduct electricity when molten or dissolved in water.

Carbon Tetrachloride

Carbon tetrachloride, ${\text{CCl}}_4$, is a classic example of a covalent compound. It consists of one carbon atom bonded to four chlorine atoms. Since both carbon and chlorine are non-metals, the bonding in ${\text{CCl}}_4$ is covalent. In this molecule, carbon shares one of its electrons with each of the four chlorines. This sharing of electrons allows all atoms to achieve a full valence shell, leading to a stable molecule.

Important aspects about ${\text{CCl}}_4$:

• It is a non-polar molecule
• Has a tetrahedral structure
• Does not conduct electricity

Carbon tetrachloride was once widely used in fire extinguishers and as a cleaning agent, but its use has declined due to its toxicity and harmful environmental effects.

Calcium Hydride

Calcium hydride, ${\text{CaH}}_2$, is an example of a compound formed by ionic bonding. It consists of calcium, a metal, and hydrogen, a non-metal. In forming ${\text{CaH}}_2$, the calcium atom loses two electrons to become a ${\text{Ca}}^{2+}$ ion, while each hydrogen atom gains one electron to become ${\text{H}}^{-}$ ions. The opposite charges attract each other, resulting in a strong ionic bond.

Key points about ${\text{CaH}}_2$:

• Ionic compound
• Consists of ${\text{Ca}}^{2+}$ and ${\text{H}}^{-}$ ions
• Used as a reducing agent in chemical reactions
• Reacts with water to produce hydrogen gas

Understanding ${\text{CaH}}_2$ is important in various industrial applications, particularly for its role in producing hydrogen gas and as a drying agent for certain chemical reactions.