Tell students that the different colored Snap Cubes (or other items you are using) are models that stand for or represent different atoms. Let students know that each group should have 4 white, 3 red, ...

Its molecules contain two oxygen atoms. Oxygen is vital for respiration, which is the process that transforms energy from glucose to energy for cells. Oxygen is necessary for burning to occur.

When two hydrogen atoms and an oxygen atom get close enough, the electron from each atom feels an attraction from the protons in the other atom's nucleus. This attraction pulls the atoms together. The ...