Question

In the following question, a positive and a negative radical is listed. Using the criss-cross method, write the formula for the compound that is formed and name the compound.

Sn⁺⁴ S^-2

Answer 1

Step-1: Identify the acidic and basic radicals or positive and negative ions:

• Positive ion or cation or basic radical: Sn⁺⁴
• Negative ion or anion or acidic radical: S^-2

Step-2: Write the valency of the ion:

• Valency is written as a positive or negative charge on the ion as a superscript on the right-hand side.

Valency of Sn⁺⁴ is 4 Valency of S^-2 is 2

Step-3: Write the valency of the ion below or above its symbol without the + or - sign:

Symbol of radical Sn S

Valency of the radical 4 2

Step-4: Transpose the valency by criss-cross:

• Criss-cross multiplication is a method where the valency of a cation is written as a subscript of anion and vice-versa.

$$\begin{gathered} \mathrm{Sn}\mathrm{S} \\ \searrow \swarrow \\ 42 \end{gathered}$$

Step-5: Write the outcome of the criss-cross and simplify by dividing using a common factor if needed

• Sn₂S₄ or SnS₂ after simplification by dividing with a common factor of 2.

Step-6: Write the chemical formula and chemical name

• Cation is written first, followed by the anion.
• The chemical formula of the compound is SnS₂
• Name of the cation is written followed by the anion.
• Cation is Stannic and anion is Sulphide
• The chemical name of the compound is Stannic sulphide.
• Sn⁺² is written as Stannous and Sn⁺⁴ is written as Stannic.