University:
High School
Course:
High School Chemistry
Academic year:

2022
Views:

212

Pages:

2
Author:

SpaceCadet101

Name:__________________________ Per:_____ Isotopes Purpose: In this lesson you will investigate isotopes and how they affect atomic mass. A proton weighs 1.0 amu (atomic mass units) and a neutron weighs 1.0 amu (atomic mass units). Complete the following: Let's say you were able to isolate ten atoms of the element boron. Below is a drawing representing the structures of the different boron atoms you would find. (Note that the size of the nucleus has been hugely exaggerated in these drawings so that you can count the protons and neutrons.) 1. 2.. 3. 4. 5. 6. 7. 8. 9. 10. 1. boron atom # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 8 # 9 # 10 # protons # neutrons # electrons 2. How many different isotopes (versions) of boron are above? How are they different? 3. How many of each type of isotope are present in the sample of ten atoms? 4. What is the atomic mass of each type of isotope? How did you arrive at your answer? 5. a) Calculate the average atomic mass of the ten boron atoms above. Show your work! b) How does your answer compare to the atomic mass of boron listed in the periodic table? 6. Imagine you were able to examine 100 atoms of boron (vs. just the 10 above). a) What isotopes (versions) would you expect to find? b) How many atoms of each type would you expect to find in a sample of 100 atoms? c) Express your answer in percentages. 7. Fill in the following table. Look carefully at the atomic mass in order to estimate the number of neutrons in each case. You will need your periodic table. Chemical Symbol Element Atomic Avg. Atomic # of Number Mass protons Lithium #of electrons 6.94 Vanadium V Argon ___ or ___ 23 Ar #of neutrons ___ or ___ 39.9 18, 20, or 22 8. Looking above at #7, how many isotopes (versions) does argon have? How do they differ? 9. Which isotope (version) of argon is most commonly found? Explain your reasoning. 10. If you somehow managed to have a single atom of lithium isolated, how many neutrons will it probably have in its nucleus? Explain. 11. Explain why the atomic masses listed in the periodic table are not usually whole numbers. 12. Identify all the numbers in the following methods of distinguishing isotopes: Hyphen notation Nuclear Notation 17 8 O Oxygen - 17 13. Which of the subatomic particles (protons, neutrons, or electrons) ALWAYS identifies an element, and thus can NEVER change for that element? 14. Hyphen Notation Example Hydrogen-1 Hydrogen-2 Atomic # Average Atomic mass Mass # # of Protons # of Electrons # of Neutrons 1 1.01 1 1 1 0 Nuclear Notation 1 1 3 1 ________- ___ H H Fluorine-19 Argon-__ ________- ___ _______- ___ 40 18 20 36 18 Ar