Question

Magnesium ions carry a \(2+\) charge, and chloride ions carry a 1 - charge. What is the chemical formula for the ionic compound magnesium chloride?

Short answer

MgCl₂

Step-by-step solution

Determine Ion Charges

First, we need to determine the charges of the ions involved. Magnesium ions (Mg) have a charge of \(2+\), and chloride ions (Cl) have a charge of \(1-\). This means each magnesium ion can balance with two chloride ions to neutralize the charges.

Balance the Charges

Since each magnesium ion has a \(2+\) charge, and each chloride ion has a \(1-\) charge, we need two chloride ions to balance one magnesium ion. This ensures the total positive charge equals the total negative charge for the compound to be neutral.

Write the Chemical Formula

The chemical formula is determined by the ratio of ions needed to balance the charges. From Step 2, we learned that we need one magnesium ion for every two chloride ions. Therefore, the chemical formula of magnesium chloride is \(\text{MgCl}_2\).

Key concepts

Ions and Charges

Ions are atoms or molecules that carry an electrical charge due to the gain or loss of electrons. They are crucial in chemical reactions and the formation of compounds. The charge of an ion depends on the number of electrons that have been removed or added to an atom.

• Positive ions, or cations, are formed when an atom loses one or more electrons. For example, magnesium becomes a cation with a charge of \(2+\) when it loses two electrons.
• Negative ions, or anions, occur when an atom gains one or more electrons. Chlorine, for example, gains an electron to form an anion with a charge of \(1-\).

Charges on ions dictate how they interact with other ions. Oppositely charged ions attract each other, leading to the formation of ionic compounds.

Ionic Compounds

Ionic compounds consist of positively and negatively charged ions bonded together through electrostatic forces. These compounds usually form between metals and non-metals.
When forming ionic compounds, the total positive charge must equal the total negative charge, resulting in a neutral compound.

• Magnesium chloride (\(\text{MgCl}_2\)) is an example of an ionic compound, where one magnesium ion (\(\text{Mg}^{2+}\)) pairs with two chloride ions (\(\text{Cl}^-\)) to balance charges.
• The resulting formula \(\text{MgCl}_2\) reflects the ratio of magnesium ions to chloride ions.

This type of bonding is very strong, giving ionic compounds characteristics such as high melting and boiling points.

Balancing Chemical Equations

Balancing chemical equations ensures that the same number of each type of atom exists on both sides of the equation, adhering to the law of conservation of mass.
In the context of ionic compounds, balancing involves ensuring that the sum of positive and negative charges in the compound is zero. This reflects the actual formula for the compound to be neutral.

• For magnesium chloride, each \(\text{Mg}^{2+}\) ion requires two \(\text{Cl}^-\) ions to balance the charges, leading to the formula \(\text{MgCl}_2\).
• Correctly balanced equations help us understand the proportions and amounts of reactants and products involved in chemical reactions.

Always check your balanced equation to validate that it effectively represents the conservation of charge and mass.