Question

Magnesium forms both an oxide and a nitride when burned in air. Discuss the formation of magnesium oxide and magnesium nitride when magnesium atoms react with oxygen and nitrogen atoms.

Short answer

When magnesium is burned in the air, it forms magnesium oxide and magnesium nitride through ionic bonding. Magnesium reacts with oxygen to form magnesium oxide (MgO) according to the equation: \(2Mg + O_2 \rightarrow 2MgO\). Magnesium also reacts with nitrogen to form magnesium nitride (Mg₃N₂) according to the equation: \(3Mg + N_2 \rightarrow Mg_3N_2\). Magnesium oxide is a white powdery solid, while magnesium nitride is a yellow powdery solid.

Step-by-step solution

Identify the reactants and products

In order to discuss the formation of magnesium oxide and magnesium nitride, we first need to identify the reactants and products in each reaction. The reactants are magnesium (Mg), oxygen (O₂), and nitrogen (N₂). The products will be magnesium oxide (MgO) and magnesium nitride (Mg₃N₂).

Write the chemical reaction for the formation of magnesium oxide

The chemical reaction for the formation of magnesium oxide occurs between magnesium and oxygen. The balanced equation for this reaction is: \[ 2Mg + O_2 \rightarrow 2MgO \]

Write the chemical reaction for the formation of magnesium nitride

The chemical reaction for the formation of magnesium nitride occurs between magnesium and nitrogen. The balanced equation for this reaction is: \[ 3Mg + N_2 \rightarrow Mg_3N_2 \]

Discuss the formation of magnesium oxide

When magnesium reacts with oxygen, the magnesium atoms lose two electrons (oxidation) to form Mg²⁺ ions. In the process, oxygen gains two electrons (reduction) to form O²⁻ ions. The electrostatic attraction between these oppositely charged ions leads to the formation of the ionic compound magnesium oxide (MgO). Magnesium oxide is formed as a white powdery solid when magnesium is burned in the presence of oxygen in the air.

Discuss the formation of magnesium nitride

When magnesium reacts with nitrogen, the magnesium atoms lose three electrons (oxidation) to form Mg³⁺ ions. Nitrogen gains three electrons (reduction) to form N³⁻ ions. The electrostatic attraction between these oppositely charged ions leads to the formation of the ionic compound magnesium nitride (Mg₃N₂). Magnesium nitride is formed as a yellow powdery solid when magnesium is burned in the presence of nitrogen in the air. In summary, when magnesium is burned in the air, it reacts with both oxygen and nitrogen, forming magnesium oxide and magnesium nitride through ionic bonding.

Key concepts

Formation of Magnesium Oxide

Understanding the formation of magnesium oxide is an excellent illustration of a basic chemical reaction. This reaction involves magnesium, a silvery-white metal, and oxygen, a gas found abundantly in the Earth's atmosphere. When magnesium atoms encounter oxygen, a chemical reaction ensues, and the result is the compound magnesium oxide (MgO).
In this process, each magnesium atom loses two electrons. This electron loss is an oxidation reaction, which transforms the neutral magnesium atoms into positively charged magnesium ions (Mg²⁺). Conversely, the oxygen molecule, composed of two oxygen atoms (O₂), accepts these electrons, undergoing reduction. Each oxygen atom gains two electrons and forms two negative oxide ions (O²⁻).
The new magnesium ions and oxide ions are held together strongly by ionic bonds, resulting in the formation of solid magnesium oxide, which appears as a white powder. This compound is often used in refractory materials due to its high melting point and ability to withstand extreme temperatures.

Formation of Magnesium Nitride

Similar to the formation of magnesium oxide, magnesium nitride is produced through the chemical reaction of magnesium with nitrogen. However, nitrogen is a bit more challenging to react with due to its triple bond, making it less reactive compared to oxygen.
During the reaction, magnesium atoms transfer three electrons to nitrogen atoms, a process that is called oxidation. This occurrence turns the magnesium atoms into Mg³⁺ ions, while the nitrogen molecule (N₂), which consists of two nitrogen atoms, splits and each atom gains three electrons to become N³⁻ ions. This is an example of reduction.
The resulting Mg³⁺ and N³⁻ ions are then gripped together by the force of ionic bonding, leading to the yellow solid known as magnesium nitride (Mg₃N₂). Though not as common as magnesium oxide, magnesium nitride is utilized in specific industrial applications where its properties, such as its high hardness, are beneficial.

Ionic Bonding

Ionic bonding is the electrostatic attraction between positively and negatively charged ions. It's a fundamental concept in understanding how compounds form from their elements.
For instance, when magnesium burns in air, it forms two different ionic compounds through reactions with oxygen and nitrogen. In both magnesium oxide and magnesium nitride, the essential mechanism is the transfer of electrons from magnesium to the nonmetal (oxygen or nitrogen), leading to the formation of positive magnesium ions and negative nonmetal ions. These ions are then strongly attracted to each other, forming the ionic bond.
This type of chemical bond is responsible for the formation of many salts and minerals and is key to the structure and properties of these substances. For example, the high stability and melting points of magnesium oxide and magnesium nitride are due to the strong ionic bonds that hold their ions together.

Oxidation and Reduction

Oxidation and reduction, often referred to together as redox reactions, are processes that involve the transfer of electrons between substances. Oxidation is the loss of electrons, while reduction is the gain of electrons. It is important to remember that these two processes always occur together; if one substance is oxidized, another must be reduced.
In the context of magnesium reacting with oxygen and nitrogen to form magnesium oxide and magnesium nitride, respectively, we see clear examples of redox reactions. Magnesium is oxidized as it loses electrons to form Mg²⁺ or Mg³⁺ ions. In contrast, the oxygen is reduced to form O²⁻ ions for creating magnesium oxide, and nitrogen is reduced to form N³⁻ ions to produce magnesium nitride.
Understanding the intricacies of redox reactions provides insight into the behavior and characteristics of different elements and compounds, and is crucial for predicting the outcomes of chemical reactions.