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