Question

Magnesium reacts with an element $(X)$ to form an ionic compound. If the ground state electronic configuration of $( X )$ is $1 s ^{2} 2 s ^{2} 2 p ^{3}$, the simplest formula for this compound is

• A. $Mg_3X_2 $
• B. $Mg_2X_3 $
• C. $Mg_2X $
• D. $MgX_2 $

Answer 1

The Correct Option is A

To determine the simplest formula for the ionic compound formed between Magnesium (Mg) and an element X with the given electronic configuration, we need to follow these steps:

1. Identify the Element X:

   The electronic configuration of element X is \(1s^2 2s^2 2p^3\). This corresponds to the element Nitrogen (N) in the periodic table. Nitrogen has an atomic number of 7.

2. Determine the Valency of X:

   Nitrogen has 5 electrons in its outer shell (\(2s^2 2p^3\)). To achieve a stable octet, Nitrogen needs to gain 3 electrons, thus its valency is 3. Therefore, Nitrogen will typically form a \(3-\) anion.

3. Valency of Magnesium:

   Magnesium has an electronic configuration of \(1s^2 2s^2 2p^6 3s^2\). It loses 2 electrons to achieve a stable configuration, hence forming a \(2+\) cation.

4. Determine the Compound Formula:

   To form a neutral ionic compound, the total positive charge must equal the total negative charge. We have:

   • 3 Magnesium ions (\(3 \times 2+ = 6+\))
   • 2 Nitrogen ions (\(2 \times 3- = 6-\))

   Therefore, the simplest formula that balances these charges is \(Mg_3N_2\).

5. Conclusion:

   The simplest formula for the compound formed between Magnesium and Nitrogen (element X) is \(Mg_3X_2\), matching the correct answer given as $Mg_3X_2 $.