SC-100 Class 13 Review Questions

1. SC-100 Class 13 Review Questions • 1. One difference between the motion of electrons in an atom and the motion of planets in the solar systems is that • a. gravity holds the planets in orbit while centripetal force holds the electrons. • b. planetary orbits are quantized, electron orbits are not. • c. Brownian motion applies to planets but not electrons. • d. planets can change their orbits and electrons cannot. • e. All of the above apply to both planets and electrons.

2. SC-100 Class 13 Review Questions • 2. Materials made from a single type of atom that cannot be broken down any further are called • a. atoms. • b. elements. • c. molecules. • d. solutions. • e. compounds.

3. SC-100 Class 13 Review Questions • 3. The fundamental building block for all matter; the smallest representative sample of a substance that maintains chemical identity. • a. atom • b. element • c. molecule • d. electron • e. compound

4. SC-100 Class 13 Review Questions • 4. We know that atoms have a nucleus because • a. alpha particles exist. • b. this is a necessary philosophical consequence of the requirement that there be change in the world. • c. the Rutherford experiment on the scattering of alpha particles from gold gives evidence for it. • d. there are no isolated monopoles in nature. • e. None of the above are evidence for the existence of the nucleus.

5. SC-100 Class 13 Review Questions • 5. Electrons in the Bohr atom shift to a higher energy level by • a. absorbing the energy of light or heat. • b. reflecting the energy of heat or light. • c. emitting a photon. • d. producing an individual electromagnetic wave. • e. Electrons in the Bohr atom cannot change energy states.

6. SC-100 Class 13 Review Questions • 6. Each electron shell corresponds to a different • a. electron. • b. element. • c. ion. • d. atom. • e. energy level.

7. SC-100 Class 13 Review Questions • 7. If an electron moves from a higher energy shell to a lower energy shell • a. a photon is emitted. • b. a photon is absorbed. • c. an observer will see light. • d. the electron disappears between shells. • e. a & c & d

8. SC-100 Class 13 Review Questions • 8. In the periodic table of the elements, the atomic number equals • a. the number of protons in the nucleus. • b. the number of neutrons in the nucleus. • c. the number of electrons in the outer shell. • d. the mass of the atom. • e. the mass of the photon.