1) The atomic masses of ^203Tl and ^205Tl are 202.972336 and 204.974410 amu, res

Question

1) The atomic masses of ^203Tl and ^205Tl are 202.972336 and 204.974410 amu, respectively. The average atomic mass of thallium is 204.383 amu. Calculate the natural abundances of these two isotopes

% abundance of ^203Tl?

% abundance of ^205Tl?

2) Determine the mass number of the following

(a) a boron atom with 5 neutrons

(b) a magnesium atom with 14 neutrons

(c) a bromine atom with 46 neutrons

(d) a mercury atom with 116 neutrons

3) write the appropriate nuclear symbol for each of the following isotopes:

(a) Z=11, A=23

(b) Z=28, A=64

(C) Z=50, A=115

(D) Z=20, A=42

show work please

Explanation / Answer

1)

Let x be the percent abundance of isotope ^203 Ti

Let 1 - x be the percent abundance of isotope ^205 Ti

(202.972336)(x) + (204.974410)(1 - x) = 204.383

Solve for x:

202.972336x + 204.974410 - 204.974410x = 204.383

-2.002074x = -0.59141

x = 0.295

Percent of isotope ^203 Ti = 0.295 x 100% = 29.5%

Percent of isotope ^205 Ti = 0.705 x 100% = 70.5%

2)

a) mass number = protons + neutrons = 5 + 5 = 10 amu

b) mass number = protons + neutrons = 12 + 14 = 26 amu

c) mass number = protons + neutrons = 35 + 46 = 81 amu

d) mass number = protons + neutrons = 80 + 16 = 96 amu

3)

a) Z = atomic number and A = atomic mass ... nuclear symbol is Na

b) nuclear symbol is Ni

c) nuclear symbol is Sn

d) nuclear symbol is Ca

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