Question

Play a game for writing formula.

Example 1: Make placards with symbols and valencies of the elements separately. Each student should hold two placards, one with the symbol in the right hand and the other with the valency in the left hand. Keeping the symbols in place, students should criss-cross their valencies to form the formula of a compound.

Answer 1

Game: Writing Chemical Formulae Using Placards

Objective: To form the correct chemical formula for a compound by using symbols and valencies of elements.

Instructions:

1. Step 1: Prepare placards

   • Create placards with the symbol of an element written on one side and the valency of that element on the other side.
   • Each student will hold two placards, one with the element’s symbol in their right hand and the other with its valency in their left hand.

2. Step 2: Select two elements

   • For example, let’s pick Magnesium (Mg) and Chlorine (Cl).
   • Magnesium: Symbol = Mg, Valency = +2
   • Chlorine: Symbol = Cl, Valency = -1

3. Step 3: Criss-cross the valencies

   • Keep the symbols in place, and criss-cross the valencies:
     Mg has a valency of 2, and Cl has a valency of 1.
     Criss-cross the numbers to the opposite element.

4. Step 4: Write the chemical formula

   • The valency of Magnesium (2) becomes the subscript for Chlorine, and the valency of Chlorine (1) becomes the subscript for Magnesium.
     Therefore, the chemical formula for the compound formed is MgCl₂.

5. Step 5: Continue with more elements

   • Repeat this process with different pairs of elements to form various compounds.