Fill in the Blanks for the following Table

 Atom Name Number Neutrons Number Electrons Number Protons Nuclide Symbol w/charge (if one) Oxygen -16 8 8 8 16O Oxygen- 18 10 10 8 18O-2 Iodine-127 74 54 53 127I- Carbon-14 8 6 6 14C Iron-56 30 24 26 56Fe+2 Iron-54 28 24 26 54Fe+2 Iorn-54 28 23 26 54Fe+3 Lead 125 78 82 207Pb+4 Strontium-90 52 38 38 90Sr Barium- 140 84 54 56 140Ba+2

1.   Calculate the atomic weight of neon (to the correct number of significant figures) composed of three naturally occurring isotopes with the following natural abundances and masses:

a.       90.51% neon-20 (mass = 19.992 amu)

b.      0.27% neon-21 (mass = 20.993 amu)

c.       9.22% neon-22 (mass = 21.991 amu)

2.  Silicon has three naturally occurring isotopes.  Silicon-28 is 92.2% abundant and has a mass of 27.979 amu, silicon-29 is 4.705% abundant and has a mass of 28.968 amu, and silicon-30 is 3.10% abundant and has a mass of 29.957 amu.  What is the average mass of silicon?

3.  An element has two naturally occurring isotopes.  Isotope 1 has a mass of 106.905 amu and a relative abundance of 51.8%.  Isotope 2 has a mass of 108.904 amu and a relative abundance of 48.2%.  Find the atomic weight of this element and, by comparison to the periodic table, identify it.

4.  A fictitious element has two naturally occurring isotopes and has an atomic weight of 29.5 amu.

a.   If the natural abundance of isotope 1 is 33.7%, what is the natural abundance of isotope 2?

b.      If the mass of isotope 2 is 30.0 amu, what is the mass of isotope 1?

5.  Chlorine has two naturally occurring isotopes.  Chlorine-35 has a mass of 34.969 amu and a relative abundance of of 75.53%.  Use the atomic weight of chlorine to determine the mass of the second chlorine isotope.

Answers:  1)  20.18 amu     2)  29.0 amu    3)  107.9 amu = Ag      4)  a)  66.3%

b)  29 amu    5)  37.0 amu