Provide the correct IUPAC name for LiSCN. (I) (II) (III) (IV) hexa- di- hepta- penta- octa- tri- mono- tetra- lithium thiocyanate sulfide cyanide sulfur nitride carbide carbon thiosulfate nitrogen hydrate acid
The Correct Answer and Explanation is:
Correct IUPAC name for LiSCN: Lithium thiocyanate
Explanation
LiSCN is an inorganic compound composed of lithium (Li⁺) as a cation and the thiocyanate ion (SCN⁻) as an anion.
To determine its IUPAC name, we break it down:
- Cation: Lithium (Li⁺)
- Lithium is an alkali metal found in Group 1 of the periodic table.
- It forms a +1 charge and is named simply as “lithium” in ionic compounds.
- Anion: Thiocyanate (SCN⁻)
- The SCN⁻ ion is called thiocyanate, a pseudohalide ion.
- It consists of a sulfur (S), carbon (C), and nitrogen (N) atom.
- The structure is often written as S–C≡N or N≡C–S, and depending on the bonding arrangement, it can exist in two resonance forms: thiocyanate (SCN⁻) and isothiocyanate (NCS⁻). However, in LiSCN, the SCN⁻ acts as thiocyanate.
The IUPAC naming convention for simple ionic compounds is:
[Name of cation] [Name of anion]
Therefore, the compound LiSCN is named lithium thiocyanate.
Why not other options?
- The compound contains no prefixes like hexa, tetra, or mono because these are only used for covalent (non-metal + non-metal) compounds, not ionic ones.
- It does not contain multiple elements requiring prefixes like “di-” or “tri-.”
- It is not an acid, so naming conventions like “thiosulfate acid” or “hydrate” do not apply.
- It does not contain “sulfide,” “cyanide,” “nitride,” “carbide,” or “thiosulfate” individually, but rather the specific polyatomic ion thiocyanate.
Conclusion:
The correct IUPAC name of LiSCN is lithium thiocyanate.
