Molecular Models and Balancing Equations: Seventh Grade Hands-On Chemistry

In 1789 Antoine Lavoisier identified the Law of Conservation of Mass with his discovery that mass cannot be created or destroyed in a chemical reaction. This finding laid the foundation for modern chemistry. Recently, Mount Madonna School seventh grade students demonstrated their awareness of this essential concept by balancing chemical equations. To work the equations, students selected and arranged cards, each with either a number or one piece of the mathematical statement, into balanced equations.

“Balancing equations can be a bit like solving a puzzle,” observed student Amelie Zands. “Everything, each piece, depends on the others.”

Classmate Luc Mattern said being able to layout the cards on the table in front of him makes it easier to understand. “I could interact with my work,” said Mattern, “and not only see the equation, but also feel it.”

Student Izaak Ocampo-Sobkoviak agreed.

“Having the equation in front of you helped, because you could rearrange it to make more sense,” he said.

Through this activity, students showed that the number of atoms at the beginning of a chemical reaction is the same as the number of atoms at the end of the reaction.

“I learned that in order to balance an equation you have to add coefficients,” commented student Kinsey Don Carlos, “to make sure there is the same number of each type of atom on each side.”

To help the students better visualize the number of atoms in each element, on each side of the equation, they also built models of the molecules in the chemical reactions using molecular models.

“The students worked hard from beginning to end during this hands-on lab,” said teacher Hilary Alvarado. “By the end of class, they showed a solid understanding of what it means to balance a chemical equation.”


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Nestled among the redwoods on 375 acres, Mount Madonna School (MMS) is a community of learners dedicated to creative, intellectual, and ethical growth. MMS supports its students in becoming caring, self-aware, discerning and articulate individuals; and believe a fulfilling life includes personal accomplishments, meaningful relationships and service to society. The CAIS and WASC accredited program emphasizes academic excellence, creative self-expression and positive character development. Located on Summit Road between Gilroy and Watsonville. Founded in 1979.