SC15.8.6

Science (2015) Grade(s): 8

Developing and Using Models

Energy and Matter

Students know:

Substances react chemically in characteristic ways.
In a chemical reaction, the atoms that make up the original substances (reactants) are regrouped into different molecules, and these new substances (products) have different properties from those of the original substances (reactants).
In a chemical reaction, the total number of each type of atom is conserved, and the mass does not change. In a chemical reaction, each molecule in each of the reactants is made up of the same type(s) and number of atoms.
In a chemical reaction, the number and types of atoms that make up the products are equal to the number and types of atoms that make up the reactants.
Each type of atom has a specific mass, which is the same for all atoms of that type.

Students are able to:

Develop a model, diagram, or digital simulation in which they identify the relevant components for a given chemical reaction.
Describe relationships between the components.
Use the model to describe that the atoms that make up the reactants rearrange and come together in different arrangements to form the products of a reaction.
Use the model to provide a causal account that mass is conserved during chemical reactions because the number and types of atoms that are in the reactants equal the number and types of atoms that are in the products, and all atoms of the same type have the same mass regardless of the molecule in which they are found.

Students understand that:

In a chemical reaction, the atoms of the reactants are regrouped into different molecules, and these products have different properties from those of the original reactants.
Mass is conserved during chemical reactions and the mass of reactants is equal to the mass of the products.