Problem 34 - Chemistry The Science in Context

Question

Draw the Lewis symbol of an ion that has the following: a. \(1-\) charge and 8 valence electrons b. \(1+\) charge and 5 valence electrons

Step-by-Step Solution

Answer

Question: Draw the Lewis symbols for the following ions: (a) an ion with 8 valence electrons and a 1- charge, (b) an ion with 5 valence electrons and a 1+ charge. Answer: The Lewis symbols for the given ions are as follows: (a) Oxide ion (O^(1-)): .. O: : : .. (b) Nitrogen ion (N^(1+)): . N: :

Step 1: Identify the elements based on the number of valence electrons and charge

To identify the elements, we can use the periodic table to match the given information about valence electrons and charge. a. The ion has 8 valence electrons and \(1-\) charge. By referring to the periodic table, we can find that this ion is an oxide ion (O\(^{1-}\)). b. The ion has 5 valence electrons and a \(1+\) charge. By referring to the periodic table, we can find that this ion is a nitrogen ion (N\(^{1+}\)).

Step 2: Draw the Lewis symbols

Now that we have identified the elements, we can draw their Lewis symbols by placing the given number of valence electrons as dots around the symbols. a. The oxide ion (O\(^{1-}\)) has 8 valence electrons. We will place these electrons around the oxygen symbol (O) as follows: .. O: : : .. b. The nitrogen ion (N\(^{1+}\)) originally had 5 valence electrons, but due to its \(1+\) charge, it lost one electron, leaving it with only 4 valence electrons. We will place these electrons around the nitrogen symbol (N) as follows: . N: : Thus, the Lewis symbols for the given ions are as shown above.

Key Concepts

Valence Electrons

Valence electrons are the outermost electrons in an atom and play a key role in chemical bonding. They are found in the outer shell of an atom and are responsible for the formation of bonds between atoms. Valence electrons are important because they determine an element’s chemical properties and its ability to bond with other atoms.

• For example, oxygen has 6 valence electrons, while nitrogen has 5.
• An atom’s reactivity is often determined by how close it is to having a full set of 8 valence electrons, known as a stable octet.

When an atom gains or loses electrons, it forms ions, which impacts its valence electron count and ultimately its chemical characteristics. Understanding valence electrons helps in drawing Lewis structures, which display the electrons and potential bonds.

Ions

Ions are charged atoms or molecules that have gained or lost electrons. When an atom gains electrons, it becomes a negatively charged ion, or anion; when it loses electrons, it becomes a positively charged ion, or cation.

• Anions have more electrons than protons, while cations have fewer electrons than protons.
• This gain or loss of electrons allows atoms to achieve a full valence shell and greater stability.

Ions play a crucial role in chemical reactions and the formation of compounds. By using Lewis structures, we can visualize the electron transfer that turns neutral atoms into ions.

Oxide Ion

An oxide ion is derived from an oxygen atom that has gained additional electrons to achieve a stable configuration. For the oxide ion, oxygen gains two electrons, giving it a total of 8 valence electrons, thus forming the ion O^{2-}.

• The standard electronic configuration of oxygen is 1s^2 2s^2 2p^4.
• By acquiring two extra electrons, oxygen achieves a full outer shell (2s^2 2p^6), matching the noble gas neon.

In a Lewis structure, an oxide ion is represented by the symbol 'O' surrounded by 8 dots, indicating the complete set of valence electrons, and often includes brackets with a charge notation to show it is an ion. Understanding the formation of the oxide ion helps in visualizing oxygen’s behavior in various compounds, like oxides.

Nitrogen Ion

A nitrogen ion is formed when a nitrogen atom loses electrons, most commonly to achieve a stable full outer shell, or attempting to. A nitrogen ion with a positive charge, like N^{1+}, has lost one of its original electrons, leaving it with 4 valence electrons.

• Nitrogen's usual electronic configuration is 1s^2 2s^2 2p^3.
• By losing an electron, nitrogen is trying to achieve a more stable electron configuration, although it does not achieve a full octet.

The representation of a nitrogen ion lacking one electron with a positive charge would be using the symbol 'N' with 4 surrounding dots (for 4 electrons left) and a finished charge notation. This illustrates how nitrogen can participate in ionic bonding, giving insight into its behavior in nitrogenous compounds.