Problem 8 - Chemistry: The Central Science in SI Units, Global Edition

Question

An element X reacts with \(\mathrm{F}_{2}(g)\) to form the molecular product shown here. (a) Write a balanced equation for this reaction (do not worry about the phases for \(\mathrm{X}\) and the product). (b) Do you think that \(\mathrm{X}\) is a metal or nonmetal? [Section 7.6\(]\)

Step-by-Step Solution

Answer

The molecular product formed when element X reacts with F2 gas is XF2. The balanced chemical equation for the reaction is: \(X + \mathrm{F_2} \rightarrow XF_2\). Since XF2 has covalent bonding, which typically forms between nonmetals, we can deduce that element X is likely a nonmetal.

Step 1: Identify the Molecular Product formed

Given the information in the question, we know that element X reacts with F2 gas to form the molecular product, represented by XF2. This is because each fluorine atom contributes one electron in a bond, and there should be two fluorine atoms to complete the bond with the element X.

Step 2: Write a balanced chemical equation

Now that we know the molecular product, we can write a balanced chemical equation for the reaction. The unbalanced equation can be written as: \[X + \mathrm{F_2}\rightarrow XF_2\] To balance the equation, we need the same number of atoms of each element on both sides of the equation. The equation is already balanced as written, with one atom of element X, and two atoms of fluorine in both reactants and product: \[X + \mathrm{F_2}\rightarrow XF_2\]

Step 3: Determine whether X is a metal or nonmetal

To determine whether the element X is a metal or a nonmetal, we can look at the type of bonding present in the molecular product XF2. In XF2, there is a sharing of electrons between X and the fluorine atoms, indicating a covalent bond. Covalent bonds typically form between nonmetals, so we can deduce that element X is likely a nonmetal.

Key Concepts

Balancing Chemical Equations

Balancing chemical equations is an important skill in chemistry. It ensures that the number of atoms for each element is equal on both sides of the equation. This respects the law of conservation of mass. In the reaction of element \( X \) with \( \mathrm{F}_2 \) to form \( \mathrm{XF}_2 \), the equation is already balanced:

• There is one \( X \) atom on each side of the equation.
• There are two \( \mathrm{F} \) atoms on the reactant side (\( \mathrm{F}_2 \)) and also two \( \mathrm{F} \) atoms in the product (\( \mathrm{XF}_2 \)).

The simplicity of this process comes from understanding how to count atoms and how they need to match in both reactants and products. It's like a puzzle, making sure the pieces (atoms) fit into the same number of slots on either side.
To balance more complex equations, you may need to adjust coefficients, which are numbers placed in front of molecules or compounds in a chemical equation. This is necessary to keep the mass and atoms the same on both sides. For our equation of \( X + \mathrm{F}_2 \rightarrow \mathrm{XF}_2 \), the equation is balanced without adding any coefficients.

Covalent Bonding

Covalent bonding occurs when two atoms share electrons, forming a stable molecule. In the case of \( \mathrm{XF}_2 \), the covalent bond is formed between element \( X \) and two fluorine atoms.
Fluorine is highly electronegative, meaning it strongly attracts electrons. When it forms a bond, it typically shares one electron with \( X \). This communication creates a molecule where electrons are shared, stabilizing both atoms involved.

• Each fluorine atom provides one electron to the bond.
• Element \( X \) shares an electron with each fluorine atom, making two covalent bonds in total, one with each fluorine.

Covalent bonds often form between nonmetals. This shared electron approach differs from ionic bonds, which involve the transfer of electrons from one atom to another. Here in \( \mathrm{XF}_2 \), the shared electrons suggest a nonmetallic nature for \( X \), likely contributing to a molecular structure rather than a crystalline ionic framework. Covalent bonding can occur as a single bond, double bond, or even a triple bond, depending on how many pairs of electrons are shared.

Metals and Nonmetals

In the periodic table, elements are broadly categorized as metals or nonmetals. This classification is based on their physical and chemical properties. Nonmetals, like those forming covalent bonds, are essential for understanding reactions such as the one we see with \( \mathrm{XF}_2 \).
Characteristics of nonmetals:

• They often have higher electronegativity values, indicating a tendency to attract electrons.
• They usually have lower melting and boiling points than metals.
• Nonmetals can form covalent bonds by sharing electrons.

Given the covalent nature of \( \mathrm{XF}_2 \), it's reasonable to deduce that \( X \) is a nonmetal. This is because metals typically form ionic bonds, whereas the presence of electron-sharing in \( \mathrm{XF}_2 \) is indicative of nonmetal behavior.
Metals, on the other hand, are good conductors of electricity and heat, generally have a shiny appearance, and are malleable. They tend to lose electrons to form positive ions. Understanding these distinctions helps to predict the kind of compounds and reactions elements can participate in.