2. Atoms Isotopes Average Atomic Mass Development of Atom 10 20 30 40 50 40 30 20 10 50 40 30 20 10 50 40 30 20 10

3. Atoms – 10 Points QUESTION: What are the three subatomic particles that make up the atom? ANSWER: Protons, Neutrons, Electrons

4. Atoms – 20 Points QUESTION: What is calculated by adding the number of protons and the number of neutrons of an element? ANSWER: Mass Number

5. Atoms – 30 Points QUESTION: “Mass is neither created nor destroyed” is what law and who discovered it? ANSWER: Law of Conservation of Mass by Antoine Lavoisier

6. Atoms – 40 Points QUESTION: How many electrons can the third energy level hold? ANSWER: 18

7. Atoms – 50 Points QUESTION: What is the Law of Definite Composition? ANSWER: The law that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.

8. Isotopes – 10 Points QUESTION: What causes the difference in the masses of isotopes? ANSWER: The Neutrons

9. Isotopes – 20 Points QUESTION: What is the mass number of an element that contains 41 protons and 44 neutrons? ANSWER: 85

10. Isotopes – 30 Points QUESTION: 102 50 Sn has how many protons? ANSWER: 50

11. Isotopes – 40 Points QUESTION: What is the nuclear symbol for the isotope of oxygen which has 9 neutrons and 10 electrons? ANSWER: 17 8 O 2-

12. Isotopes – 50 Points QUESTION: What are the three isotopes of Hydrogen? ANSWER: Protium, dueterium, tritium

13. Average Atomic Mass – 10 Points QUESTION: What is the average atomic mass of Carbon if 98.89% exists as 12 C and 1.11% exists as 13 C? ANSWER: 12.01 ~ 12 amu

14. Average Atomic Mass – 20 Points QUESTION: What is the average atomic mass of Boron if it exists as 19.90% 10 B and 80.10% 11 B? ANSWER: 10.801 ~ 11 amu

15. Average Atomic Mass – 30 Points QUESTION: What is the average atomic mass of Calcium if 24% exists as 41 Ca, 60% exists as 40 Ca, and 16% exists as 39 Ca? ANSWER: 40.1 ~ 40. amu

16. Average Atomic Mass – 40 Points QUESTION: Cadmium has five common isotopes: 110 Cd (8.0%), 112 Cd (7.8%), 113 Cd (73.4%), 114 Cd (5.5%), 115 Cd (5.3%). What is the average atomic mass of cadmium? ANSWER: 112.843 ~ 113 amu

17. Average Atomic Mass – 50 Points QUESTION: Lithium has two isotopes with atomic masses of 6.674 amu and 7.254 amu. Estimate the abundance of these two isotopes if the atomic mass of naturally occurring lithium is 6.941. ANSWER: 53.97%, 46.03%

18. Development of Atom – 10 Points QUESTION: Who discovered the electron in 1897 by using a cathode ray tube? ANSWER: J.J. Thomson

19. Development of Atom – 20 Points QUESTION: Who determined the exact charge of an electron through the Oil Drop Experiment? ANSWER: Robert Milikan

20. Development of Atom – 30 Points QUESTION: Who discovered energy levels? ANSWER: Niels Bohr

21. Development of Atom – 40 Points QUESTION: Who discovered the neutron? ANSWER: Chadwick

22. Development of Atom – 50 Points QUESTION: Who realized there were positively charged particles moving in the direction opposite to cathode rays, which caused them to discover the proton? ANSWER: Goldstein and Wein