What is the correct name for the compound S2Cl2?
a. disulfur chlorate
b. disulfur dichloride
c. disulfur dichlorine
d. sulfur(I) chloride
The correct answer and explanation is :
The correct answer is:
b. disulfur dichloride
Explanation (300+ words):
The compound S₂Cl₂ is named disulfur dichloride, and here’s how this name is systematically derived according to the rules of naming binary molecular compounds (compounds composed of two nonmetals):
1. Identify the Elements Present
S₂Cl₂ contains:
- Sulfur (S)
- Chlorine (Cl)
Both are nonmetals, so we use the prefix system for molecular (covalent) compounds.
2. Use Prefixes to Indicate Number of Atoms
In naming binary molecular compounds, Greek prefixes are used to show the number of atoms of each element in the compound:
- 1 = mono-
- 2 = di-
- 3 = tri-
- 4 = tetra-
- … and so on.
In S₂Cl₂:
- There are 2 sulfur atoms → prefix “di”
- There are 2 chlorine atoms → prefix “di”
3. Naming Order
The element with the lower electronegativity is named first, and sulfur is less electronegative than chlorine. So:
- Name sulfur first: disulfur
- Name chlorine second: dichloride
- Note: The second element ends in “-ide” instead of “-ine.”
So, the name becomes disulfur dichloride.
4. Why the Other Choices Are Incorrect
- a. disulfur chlorate: “Chlorate” (ClO₃⁻) is a polyatomic ion and not present in this compound.
- c. disulfur dichlorine: “Dichlorine” implies neutral Cl₂ molecules, not Cl⁻ ions in a compound.
- d. sulfur(I) chloride: This naming is used in ionic compounds with metals or transition metals that have variable charges. Sulfur is not a metal and does not form variable oxidation states in such a way in this context.
Conclusion:
The naming follows the molecular (covalent) compound rule using prefixes. Hence, the correct name of S₂Cl₂ is disulfur dichloride.