http://www.ck12.org Chapter 4. Atomic Structure
Lesson Review Questions
Recall
- Describe the contribution of Democritus to modern atomic theory.
- What happens to the total mass of a system during a chemical reaction?
- What does “fixed composition” mean with regard to chemical compounds?
- What law explains the relationships between different chemical compounds that contain only the elements
carbon and oxygen? - What are the four essential points of Dalton’s atomic theory?
Apply Concepts
- Alchemy is an ancient tradition that predated the modern science of chemistry. One goal of the alchemist was
to change base metals, such as iron or lead, into valuable metals such as gold or silver. Explain, using Dalton’s
theory, why alchemists were unable to do this.
Think Critically
- If an atom of element A has a mass of 2 units, while an atom of element B has a mass of 5 units, what would
be the ratio of element A to element B in a compound that had a mass of 11 units? - Sulfur reacts with oxygen to form two compounds. Compound A consists of 1.89 g of sulfur for every 1.89
g of oxygen. Compound B consists of 3.72 g of sulfur for every 5.57 g of oxygen. What is the lowest whole
number mass ratio of sulfur that combines with a given mass of oxygen? - Hydrocarbons are a class of organic compounds that contain only carbon and hydrogen. Methane, an important
hydrocarbon fuel, has a carbon/hydrogen mass ratio of 3:1. An 80-g sample of a hydrocarbon compound is
analyzed and found to contain 64 g of carbon. Is the hydrocarbon sample methane? Explain. - The mass of 6.02× 1023 atoms of iron is 55.85 g. What is the mass of one atom of iron?
Further Reading / Supplemental Links
- For more information about Dalton’s contributions, go to the video Early Ideas About Atoms at http://www.t
eachertube.com/viewVideo.php?title=John_Dalton_s_Atomic_Theory&video_id=228303.