Let's analyze each of the statements regarding lithium sulfide (Li₂S):
A. The atoms in lithium sulfide are held together by bonds.
- This statement is correct. In lithium sulfide, lithium and sulfur are held together by ionic bonds, where lithium donates electrons to sulfur.
B. A molecular model of lithium sulfide would have two spheres.
- This statement is incorrect. Lithium sulfide is an ionic compound, not a molecular compound. Ionic compounds do not form discrete molecules but rather a lattice structure.
C. Both lithium and sulfur form positive ions.
- This statement is incorrect. In lithium sulfide, lithium (Li) forms a positive ion (Li⁺) whereas sulfur (S) forms a negative ion (S²⁻). So, only lithium forms positive ions.
D. The chemical formula for lithium sulfide is LiS.
- This statement is incorrect. The correct chemical formula for lithium sulfide, which consists of two lithium ions for each sulfur ion, is Li₂S.
Therefore, the correct statement about lithium sulfide is: A. The atoms in lithium sulfide are held together by bonds.