Question

Describe the formation of solid magnesium chloride \(\left(\mathrm{MgCl}_{2}\right)\) from large numbers of magnesium and chlorine atoms.

Short answer

Solid \(\text{MgCl}_2\) forms by magnesium \(\text{Mg}\) donating electrons to chlorine \(\text{Cl}_2\), creating \(\text{Mg}^{2+}\) and \(\text{Cl}^-\) ions, which bond ionically.

Step-by-step solution

Identify the Reactants

The two reactants involved in the formation of solid magnesium chloride \(\text{MgCl}_2\) are magnesium \(\text{Mg}\) and chlorine \(\text{Cl}_2\).

Magnesium Atom Characteristics

Magnesium is in Group 2 of the periodic table and has the electron configuration \([Ne]3s^2\). Magnesium atoms have two electrons in their outer shell.

Chlorine Molecule Characteristics

Chlorine is in Group 17 of the periodic table and has the electron configuration \([Ne]3s^2 3p^5\). Chlorine molecules exist as \(\text{Cl}_2\) with each chlorine atom needing one more electron to complete its outer shell.

Electron Transfer Process

Each magnesium atom loses two electrons to form a \(\text{Mg}^{2+}\) ion. Each chlorine atom in \(\text{Cl}_2\) will gain one electron to form two \(\text{Cl}^-\) ions. The balanced equation is \(\text{Mg} + \text{Cl}_2 \rightarrow \text{MgCl}_2 \).

Formation of Ionic Bonds

The \(\text{Mg}^{2+}\) ions and \(\text{Cl}^-\) ions attract each other due to electrostatic forces, forming ionic bonds, and resulting in the ionic compound magnesium chloride \( \text{MgCl}_2 \) as a solid lattice structure.

Key concepts

Reactants in Chemical Reactions

In any chemical reaction, identifying the reactants is a crucial first step. Reactants are the starting materials that undergo a chemical change to form products. For the formation of magnesium chloride (\text{MgCl}_2\text{MgCl}\(_{2}\)), the key reactants are:

• Magnesium (Mg)
• Chlorine (\text{Cl}_2\text{Cl}\(_{2}\))

Magnesium is a shiny, silvery-white metal with the atomic number 12, found in Group 2 of the periodic table. Chlorine, on the other hand, is a greenish-yellow gas, found in Group 17 of the periodic table. When magnesium and chlorine react, they form the compound magnesium chloride through a series of steps involving electron transfer and ionic bond formation.

Electron Configuration

Understanding the electron configuration of atoms helps explain their chemical behavior.
Magnesium has the electron configuration \text{[Ne]3s^2}\text{[Ne]}3s\(^{2}\), indicating it has two electrons in its outermost shell. These are the electrons involved in chemical reactions.
Chlorine has the electron configuration \text{[Ne]3s^2 3p^5}\text{[Ne]}3s\(^{2}\) 3p\({^5}\), meaning it has seven electrons in its outermost shell and needs one more electron to achieve a stable configuration of eight electrons, similar to the noble gases.
In a chemical reaction, electron configuration changes as atoms seek stability, usually by gaining or losing electrons. For example, in the formation of magnesium chloride, magnesium loses its two outermost electrons:

Ionic Bond Formation

Ionic bond formation occurs when atoms transfer electrons to achieve stable electron configurations.
Magnesium, with two electrons in its outer shell, will lose these electrons to form a stable \text{Mg}^{2+}\text{Mg}\(^{2+}\) ion.
Chlorine, needing one electron to complete its outer shell, will gain an electron to form \text{Cl}^-\text{Cl}\(^{-}\) ions. Each chlorine molecule (\text{Cl}_2\text{Cl}\(_{2}\)) produces two \text{Cl}^-\text{Cl}\(^{-}\) ions.
The reaction can be summed up as: \text{Mg} + \text{Cl}_2 \rightarrow \text{MgCl}_2\text{Mg} + \text{Cl}\(_{2}\) \rightarrow \text{MgCl}\(_{2}\).
This process results in the formation of ionic bonds due to the strong electrostatic attraction between the \text{Mg}^{2+}\text{Mg}\(^{2+}\) cations and the \text{Cl}^-\text{Cl}\(^{-}\) anions, giving rise to a stable ionic compound, magnesium chloride (\text{MgCl}_2\text{MgCl}\(_{2}\)).