The chemical formula for calcium nitride is
A) CaN2
B) Ca3N2
C) Ca(NO2)2
D) Ca(NO3)2
The correct answer and explanation is :
The correct answer is B) Ca3N2.
Explanation:
Calcium nitride is an inorganic compound composed of calcium (Ca) and nitrogen (N). To understand why its chemical formula is Ca3N2, we need to analyze the charges of the ions involved and balance the chemical formula accordingly.
- Calcium ion (Ca²⁺): Calcium belongs to Group 2 of the periodic table, which means it typically forms a cation with a +2 charge (Ca²⁺). When calcium reacts to form compounds, it loses two electrons to achieve a stable electron configuration.
- Nitride ion (N³⁻): Nitrogen, found in Group 15, typically forms an anion with a -3 charge (N³⁻) when it gains three electrons to achieve a stable electron configuration.
To form a neutral compound, the total positive charge from the calcium ions must balance the total negative charge from the nitride ions. Let’s now find the correct ratio of calcium ions (Ca²⁺) to nitride ions (N³⁻).
- Each Ca²⁺ ion carries a +2 charge.
- Each N³⁻ ion carries a -3 charge.
We need to balance the total charges:
- To balance the charges, we would need three calcium ions (Ca²⁺) to provide a total charge of +6 (3 × +2 = +6).
- Two nitride ions (N³⁻) would give a total charge of -6 (2 × -3 = -6).
Thus, the ratio of calcium ions to nitride ions is 3:2. Therefore, the correct formula for calcium nitride is Ca3N2.
Why the other options are incorrect:
- A) CaN2: This formula does not correctly balance the charges of calcium and nitrogen.
- C) Ca(NO2)2: This formula represents calcium nitrite, which is a different compound.
- D) Ca(NO3)2: This formula represents calcium nitrate, a different compound containing nitrate ions (NO3⁻).
Thus, Ca3N2 is the correct chemical formula for calcium nitride.