- Ws 3 1 Isotopic Notation Fill In The Table All Atoms Are Neutral No Isotopic Notation Atomic Number E Electrons Mass 1 (40.05 KiB) Viewed 47 times
- Ws 3 1 Isotopic Notation Fill In The Table All Atoms Are Neutral No Isotopic Notation Atomic Number E Electrons Mass 2 (61.46 KiB) Viewed 47 times
- Ws 3 1 Isotopic Notation Fill In The Table All Atoms Are Neutral No Isotopic Notation Atomic Number E Electrons Mass 3 (41.13 KiB) Viewed 47 times
WS 3-2: Atomic Number & Atomic Mass . Each element found in nature occurs as a mixture of isotopes Isotopes of an element have the same number of protons (same Atomic Number), but differ in the number of neutrons-50, they have different masses. Table 1: Natural isotopic abundance on Earth for some elements. Isotope Abundance on Earth (%) Isotopic Mass (amu) 12C (carbon-12) 98.89 12.00 13C (carbon-13) 1.11 13.00 160 (oxygen-16) 99.76 16.00 170 (oxygen-17) 0.04 17.00 180 (oxygen-18) 0.20 18.00 1. How many Isotopes of oxygen are listed in the table? 5 2. What do isotopes of oxygen have in common? How are they different? Common Atomic # differen Atomic Mass amu. 3. If you selected one carbon atom at random, the mass of that atom is most likely to bela 4. What is the mass (in amu) of 100 carbon-12 atoms? Jan 100X12 5. If you select 100 carbon atoms at random, the total mass will likely be: a. 1200.0 amu b. Slightly more than 1200 amu c. slightly less than 1200 amu d. 1300.0 amu The average mass of a marble • In a collection of 100 marbles, 25 of the marbles have a mass of 5.00 g and 75 have a mass of 7.00 8. • The average mass of a marble is 6.50 g. The average mass can be determined by dividing the total mass of the marbles by the total number of marbles: Average mass = (25 x 5.00)+(75x7.00) = 6.50g (1) • The average mass of a marble can also be determined by first multiplying the fraction (or decimal percent) of marbles of a particular type by the mass of a marble of that type and then taking a sum over all types of marbles: 100 (2) Average mass = (0.25 x 5.00) + (0.75 x 7.00) = 6.50 g 6. Do any of the marbles from the previous example have a mass of 6.50 g?
7. Using the method shown in equation (2), calculate the average mass of a carbon atom in amu. Show your work and round your answer to 2 decimal places: Compare your answer to the "Atomic Mass of carbon shown on your Periodic Table 8. Using the method shown in equation (2) above, calculate the average mass of a boron atom in amu given the following isotopic masses and abundance. Your answer should be rounded to 2 decimal places. Isotope abundance 19.70% 80 30% Isotopic mass 10.013 amu 11.009 amu Boron-10 Boron-11 Compare your answer to the "Atomic Mass" of boron shown on your Periodic Table Additional Practice Isotopic abundances are different in other parts of the universe. Suppose that on the planet Krypton we find the following stable isotopes and abundances for boron: 108 10.013 amu 65.75% 118 11.009 amu 25.55% 128 12.014 amu 8.70% What is the value of the average atomic mass of boron on the planet Krypton?