What is the correct systematic name of the compound Mg(NO3)2?

Introduction / Context:
Systematic naming of ionic compounds follows set rules based on the cation and anion present. Understanding these rules is central to learning inorganic chemistry. This question asks you to identify the correct name for Mg(NO3)2, an ionic compound containing magnesium and the nitrate ion. It also tests your ability to distinguish nitrate from nitrite and magnesium from manganese.

Given Data / Assumptions:

• The chemical formula is Mg(NO3)2.
• The cation is Mg^2 plus and the anion is NO3 minus.
• Options mention nitrate and nitrite with magnesium and manganese.
• We assume knowledge of common polyatomic ions.

Concept / Approach:
In ionic nomenclature, the name of the cation is given first, followed by the name of the anion. Magnesium, Mg^2 plus, is a metal ion. The NO3 minus ion is called nitrate, while NO2 minus is called nitrite. The formula Mg(NO3)2 clearly contains nitrate ions, not nitrite. Manganese is a different metal with symbol Mn, not Mg. Therefore, the correct name is magnesium nitrate.

Step-by-Step Solution:
Step 1: Identify the metal ion from the formula Mg(NO3)2. The symbol Mg stands for magnesium, not manganese. Step 2: Recognise the polyatomic ion NO3 minus as nitrate, which has one nitrogen and three oxygen atoms. Step 3: Recall that nitrite has the formula NO2 minus, so it is not present in this compound. Step 4: Combine the names by placing the metal name first and the anion name second. Step 5: This gives the name magnesium nitrate for Mg(NO3)2. Step 6: The subscript 2 indicates there are two nitrate ions for each magnesium ion, but the basic name remains magnesium nitrate.

Verification / Alternative check:
You can verify by checking standard tables of ionic compounds where Mg(NO3)2 is clearly listed as magnesium nitrate. Agrochemicals and laboratory chemicals often label this compound with that name. Additionally, if you write out the dissociation of Mg(NO3)2 in water, you get magnesium ions and nitrate ions in solution, further confirming the presence of nitrate rather than nitrite.

Why Other Options Are Wrong:
Manganese nitrite: This name would correspond to a compound with Mn^2 plus or Mn^3 plus and NO2 minus ions, not Mg(NO3)2.
Magnesium nitrite: This would be Mg(NO2)2, but the given formula has NO3 groups, so nitrite is incorrect.
Manganese nitrate: This would use the metal Mn instead of Mg; the symbol in the formula is clearly Mg, so manganese is wrong.
Magnesium nitrogen oxide: This is not a standard systematic name and does not recognise the nitrate polyatomic ion.

Common Pitfalls:
A typical mistake is to confuse magnesium with manganese because their names sound similar and their symbols (Mg and Mn) look alike. Another pitfall is mixing up nitrate and nitrite, which differ by one oxygen atom. To avoid such errors, memorise the formulas and charges of common polyatomic ions and pay close attention to element symbols in chemical formulas. Reading the formula carefully before choosing the name is essential.

Final Answer:
The systematic name of Mg(NO3)2 is magnesium nitrate.