How to Name the Ionic Compound Mg3P2

TL;DR

The ionic compound with the formula Mg3P2 is named magnesium phosphide. This is determined by writing the cation, magnesium (Mg²⁺), first and the anion, phosphide (P³⁻), second, following the naming convention for ionic compounds. The compound consists of three magnesium cations and two phosphide anions, resulting in a neutral charge.

Transcript

• [Instructor] Let's get some practice naming ionic compounds. So I have a formula for an ionic compound right over here, but how would I say this? And if you get inspired, pause the video and try to work it out on your own. Well we could see that it has some magnesium, and it has some phosphorus, and the convention is, is the positive ion is writt... Read More

Key Insights

• 🈂️ Ionic compounds consist of positively charged cations and negatively charged anions.
• 🍹 The naming convention for ionic compounds requires the cation to be written first followed by the anion.
• 💁 Magnesium loses two electrons to form a +2 charge, while phosphorus gains three electrons to form a -3 charge.
• 🤙 The compound Mg3P2 is called magnesium phosphide because it contains three magnesium cations and two phosphide anions.

Questions & Answers

Q: What is the charge of magnesium and why is it the cation in the compound?

Magnesium has a charge of +2 because it belongs to group 2 of the periodic table, and alkaline earth metals tend to lose two electrons when ionized.

Q: Why is the anion in the compound phosphide?

Phosphorus, which is located on the right-hand side of the periodic table, wants to gain three electrons to complete its outermost shell. Therefore, when it ionizes, it forms phosphide with a charge of -3.

Q: How do we ensure that the compound is neutral?

The compound is neutral because the collective charge of the three magnesium ions (+6) cancels out the charge of the two phosphide anions (-6).

Q: How do we name the compound magnesium phosphide?

We name the compound by using the elemental name for the cation (magnesium) and adding the "-ide" ending to the anion (phosphide).

Summary & Key Takeaways

• The formula Mg3P2 represents an ionic compound consisting of three magnesium cations (Mg2+) and two phosphide anions (P3-).

• The cation, magnesium, is written first according to the naming convention, and the anion, phosphide, is written second.

• By following the convention and understanding the charges of the ions, we can determine the compound's name as magnesium phosphide.