Chemistry: Writing Chemical Formulas

Objectives

• Students will understand that the chemical formula identifies each constituent element by its chemical symbol.
• Students will understand that a subscript after the chemical symbol indicates the number of atoms of each element found in each discrete molecule of that compound.
• Students will recognize that the valence of an element determines the ratio that atoms will combine with one another to form a neutral compound.
• Students will understand that atoms always combine with one another in simple whole number ratios.

Vocabulary

• cation
• anion
• ionic compound
• ionic charge
• valence

About the Lesson

This lesson involves students practicing writing chemical formulas for ionic binary compounds. The activity consists of four parts:

• Students will write chemical formulas given a cation and an anion.
• Students will determine the charge of a transition metal given a formula of a compound. Students will write chemical formulas given the name of a compound.
• Students will name a compound given its formula.

• Reinforce understanding of the concept of ionic charges necessary to write the chemical formula of ionic compounds.
• Recognize that the valences of the elements determine the ratio of the elements in a compound