Section 2.3 describes the postulates of Dalton’s atomic theory. With some modifications, these postulates hold up very well regarding how we view elements, compounds, and chemical reactions today. Answer the following questions concerning Dalton’s atomic theory and the modifications made today.

a. The atom can be broken down into smaller parts. What are the smaller parts?

b. How are atoms of hydrogen identical to each other, and how can they be different from each other?

c. How are atoms of hydrogen different from atoms of helium? How can H atoms be similar to He atoms?

d. How is water different from hydrogen peroxide (H2O2) even though both compounds are composed of only hydrogen and oxygen?

e. What happens in a chemical reaction, and why is mass conserved in a chemical reaction?