To determine the correct formula for lithium sulfide, we need to consider the charges of the ions involved and how they combine to form a neutral compound.
1. Identify the charges:
- Lithium (Li) is an alkali metal and typically forms a cation with a charge of +1.
- Sulfur (S) typically forms an anion with a charge of -2.
2. Balance the charges:
- Since lithium has a charge of +1 and sulfur has a charge of -2, we need to balance the overall charge to make a neutral compound.
- To balance the charges, we need two lithium ions (each with a +1 charge) to balance one sulfide ion (with a -2 charge).
3. Write the formula:
- We place two lithium ions (Li) for every sulfide ion (S) to balance the charges.
- The correct formula is therefore [tex]\( Li_2S \)[/tex].
Now, let's look at the given options to find the correct one:
- [tex]\( Li_2Su \)[/tex]: This is incorrect because "Su" does not correspond to sulfur.
- [tex]\( LiS_2 \)[/tex]: This is incorrect because it implies there are two sulfide ions, which would result in an imbalance of charges.
- [tex]\( Li_2S \)[/tex]: This correctly represents two lithium ions paired with one sulfide ion to form a neutral compound.
- [tex]\( LiS \)[/tex]: This is incorrect because it suggests a 1:1 ratio of lithium to sulfur, which would not balance the charges.
Therefore, the correct formula for lithium sulfide is [tex]\( Li_2S \)[/tex].
