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TT 28
5. Calculate the following (show ALL work):
a). lodine is 80% 1271, 17% 1261, and 3% 1281.
Calculate the average atomic mass of iodine.
(1271)(0.80) + (1261)(0.17)+(1281)(0.3) = 1615.47amu
b)Calculate the average atomic mass of gold with the 47% being gold-197
and having a mass of 196.998amu, and 53% being gold-198 and having an
atomic mass of 197.987amu.
(196.998)(0.47) + (197.987)(0.53)= 197.52amu
c) Calculate the average atomic mass of lithium, which occurs as two
isotopes that have the following atomic masses and abundances in nature:
6.017 amu (7.30%) and 7.018 amu (92.70%).
(6.017)(0.730)+(7.018)(0.9270)= 10.9amu
6, An isotope of uranium has an atomic number of 92 and a mass number of 235.
What are the number of protons and neutrons in the nucleus of this atom?
92 protons
235-92= 143 neutrons
7. The number of protons in the nucleus of a tin atom is 50, while the number
of neutrons in the nucleus is 68. What are the atomic number and the mass
number of this isotope?
The atomic number is 50.
The mass number can be calculated adding 50 + 68 is equal to 118.
8. Explain how atoms are composed.
An atom is composed with a nucleus that have one or more negatively charged electrons
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