Determine the name of these compounds from their formulas: 1). Ni2Se3 2). P4S10
The Correct Answer and Explanation is:
Here are the names of the compounds based on their formulas:
- Ni₂Se₃ – Nickel(III) selenide
- P₄S₁₀ – Tetraphosphorus decasulfide
Explanation
To determine the names of chemical compounds from their formulas, we first need to identify whether the compound is ionic or covalent, as the naming rules differ for each.
1) Ni₂Se₃ – Nickel(III) selenide
This is an ionic compound consisting of a metal (Nickel) and a nonmetal (Selenium). In ionic compounds, we name the cation (metal) first and then the anion (nonmetal), changing the nonmetal’s ending to “-ide.”
Nickel is a transition metal, which can have multiple oxidation states, so we must determine which one it uses here.
Selenium (Se) typically has a −2 charge. There are 3 selenium atoms, each with a −2 charge, giving a total of −6.
To balance this, the 2 nickel (Ni) atoms must collectively provide +6, so each nickel must be +3.
Therefore, the compound is Nickel(III) selenide (the Roman numeral III shows the +3 charge on Ni).
2) P₄S₁₀ – Tetraphosphorus decasulfide
This is a molecular (covalent) compound composed of two nonmetals (phosphorus and sulfur). For covalent compounds, we use Greek prefixes to indicate the number of atoms:
- 4 phosphorus atoms = tetraphosphorus
- 10 sulfur atoms = decasulfide (“deca-” for 10 and “-sulfide” for sulfur)
The rule is to use the full prefix for both elements (unless the first element is only one atom, in which case the prefix is omitted).
So, P₄S₁₀ is named Tetraphosphorus decasulfide.
Summary:
- Ni₂Se₃ → Ionic compound → Transition metal with variable oxidation → Nickel(III) selenide
- P₄S₁₀ → Covalent compound → Use Greek prefixes → Tetraphosphorus decasulfide
