Chapter 2: Problem 59
Which of the following compounds are likely to be ionic? Which are likely to be molecular? \(\mathrm{SiCl}_{4}, \mathrm{LiF},\) \(\mathrm{BaCl}_{2}, \mathrm{~B}_{2} \mathrm{H}_{6}, \mathrm{KCl}, \mathrm{C}_{2} \mathrm{H}_{4}\)
Short Answer
Expert verified
Ionic: \( \mathrm{LiF}, \mathrm{BaCl}_{2}, \mathrm{KCl} \); Molecular: \( \mathrm{SiCl}_{4}, \mathrm{B}_{2} \mathrm{H}_{6}, \mathrm{C}_{2} \mathrm{H}_{4} \).
Step by step solution
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Ionic Bonds
When discussing ionic bonds, it's important to understand how they form. **Ionic bonds** arise due to the transfer of electrons from one atom to another. This usually happens between metals and non-metals.
A metal atom loses electrons to become a positively charged ion, known as a cation. A non-metal atom gains these electrons to become a negatively charged ion, or an anion. The oppositely charged ions attract each other, creating a strong electrostatic force which leads to the formation of ionic bonds.
Some characteristics of ionic compounds include high melting and boiling points, and they often dissolve in water to form aqueous solutions that conduct electricity.
To spot ionic bonds, look for combinations of metals and non-metals in a compound. For instance, in the compound \( \mathrm{LiF} \), lithium (Li) is a metal, and fluorine (F) is a non-metal, making \( \mathrm{LiF} \) a typical ionic compound.
A metal atom loses electrons to become a positively charged ion, known as a cation. A non-metal atom gains these electrons to become a negatively charged ion, or an anion. The oppositely charged ions attract each other, creating a strong electrostatic force which leads to the formation of ionic bonds.
Some characteristics of ionic compounds include high melting and boiling points, and they often dissolve in water to form aqueous solutions that conduct electricity.
To spot ionic bonds, look for combinations of metals and non-metals in a compound. For instance, in the compound \( \mathrm{LiF} \), lithium (Li) is a metal, and fluorine (F) is a non-metal, making \( \mathrm{LiF} \) a typical ionic compound.
Molecular Bonds
**Molecular bonds** are another type of chemical bonding mechanism. These bonds involve the sharing of electrons between atoms, usually non-metals. This sharing creates what are known as covalent bonds.
In covalent bonding, the mutual sharing of electrons helps each atom achieve a stable electron configuration. Typically, these compounds have lower melting and boiling points compared to ionic compounds and often don't conduct electricity in any state.
Molecular compounds can form discrete molecules, which are stable, electrically neutral clusters of atoms held together by covalent bonds. An example of this would be \( \mathrm{C}_{2} \mathrm{H}_{4} \), or ethylene, where all atoms involved are non-metals, sharing electrons to satisfy their valence shells.
In covalent bonding, the mutual sharing of electrons helps each atom achieve a stable electron configuration. Typically, these compounds have lower melting and boiling points compared to ionic compounds and often don't conduct electricity in any state.
Molecular compounds can form discrete molecules, which are stable, electrically neutral clusters of atoms held together by covalent bonds. An example of this would be \( \mathrm{C}_{2} \mathrm{H}_{4} \), or ethylene, where all atoms involved are non-metals, sharing electrons to satisfy their valence shells.
Chemical Compounds
Whether ionic or molecular, **chemical compounds** result from the combination of different elements in fixed ratios by mass. Every compound has distinct chemical and physical properties.
The nature of these properties largely depends on the type of bonding present in the compound. Ionic compounds, due to their lattice structure, tend to be more rigid and brittle. In contrast, molecular compounds, with their shared electron clouds, usually have more varied forms such as gases, liquids, or softer solids.
Understanding the type of compound is pivotal in predicting its behavior in chemical reactions, as well as its practical applications. For example, ionic compounds like \( \mathrm{KCl} \) are often used in applications requiring high stability at room temperature, whereas molecular compounds like \( \mathrm{SiCl}_{4} \) are utilized in synthesis and reactions that involve softer conditions.
The nature of these properties largely depends on the type of bonding present in the compound. Ionic compounds, due to their lattice structure, tend to be more rigid and brittle. In contrast, molecular compounds, with their shared electron clouds, usually have more varied forms such as gases, liquids, or softer solids.
Understanding the type of compound is pivotal in predicting its behavior in chemical reactions, as well as its practical applications. For example, ionic compounds like \( \mathrm{KCl} \) are often used in applications requiring high stability at room temperature, whereas molecular compounds like \( \mathrm{SiCl}_{4} \) are utilized in synthesis and reactions that involve softer conditions.
Metal and Non-metal Bonding
The nature of **metal and non-metal bonding** is foundational in distinguishing between ionic and molecular compounds. When a metal interacts with a non-metal, they typically form ionic compounds. This is because metals tend to lose electrons while non-metals aim to gain electrons to reach a stable electron configuration.
This electron transfer happens because metals usually have one or two electrons in their outermost shell, which they easily lose, while non-metals have almost full outer shells and prefer to gain electrons to complete them.
On the other hand, non-metal and non-metal bonds usually result in molecular compounds. These involve the sharing of electrons, creating covalent bonds that hold the atoms together. For example, in \( \mathrm{SiCl}_{4} \), silicon (metalloid) and chlorine (non-metal) share electrons, forming a molecular compound. Such understanding helps in predicting the mode of reaction and the type of substance formed.
This electron transfer happens because metals usually have one or two electrons in their outermost shell, which they easily lose, while non-metals have almost full outer shells and prefer to gain electrons to complete them.
On the other hand, non-metal and non-metal bonds usually result in molecular compounds. These involve the sharing of electrons, creating covalent bonds that hold the atoms together. For example, in \( \mathrm{SiCl}_{4} \), silicon (metalloid) and chlorine (non-metal) share electrons, forming a molecular compound. Such understanding helps in predicting the mode of reaction and the type of substance formed.
