Have you found videos, websites, or explanations that helped you understand this chapter? Let us know and we'll add them to "Resources" part of this page for other students to use.

What is the number of protons in Cl-35. (See PDF CH 19 SUPPLEMENT RH for meaning of Cl-35.)

If the protons change the element changes so chlorine will always have 17 protons.. never more never less because then it would'nt be chlorine it would be one of its periodic table neighbors

What is the number of neutrons?

Take the mass number 35 an subtract the number of protons 17

35-17=18

What is Z?

Z is the atomic/proton number

What is A?

A is the mass number

What is the number of protons in Cs-133? (See PDF CH 19 SUPPLEMENT RH for meaning of Cs-133.)

Caesium will always have 55 protons

What is the number of neutrons?

133-55=78

What is Z?

What is A?

Using the periodic table, what is the element when Z = 33 and A = 75?

(Input symbol, remember neon is Ne NOT ne.)

(Input symbol, remember neon is Ne NOT ne.)

Z=proton number

So find the element on the periodic table with 33 as their atomic number aka Arsenic

Using the periodic table, what is the element when the number of electrons is 28 and the charge on the ion is +3?

28 + 3 = 31 (proton)

aka Gallium

Calculate the neutron-to-proton ratio for O-17.

8:9

Does the above isotope lie within the band of nuclear stability? (Compare number of neutrons to number of protons with what is given in graph.)

Select one:

Calculate the neutron-to-proton ratio for Cu-68.

29:39

Does the above isotope lie within the band of nuclear stability?

Select one:

Calculate the neutron-to-proton ratio (to two decimal places) for Pu-239.

94:145

1.542

Identify the missing particles by balancing the mass and atomic numbers in each of the following nuclear decay equations.

Select one or more:

Does Ga-67, the above isotope, lie within the band of nuclear stability?

Select one:

See PDF CH 19 SUPPLEMENTS RH if reaction is missing.

Select one or more:

See PDF CH 19 SUPPLEMENTS RH if reaction is missing.

Select one or more:

UPPLEMENTS RH if reaction is missing.

Select one or more:

Select one or more:

Which of the following statements are true with respect to natural radioactive decay?

Select one or more:

For each of the following radioactive nuclides, predict the mode of decay from its location in the periodic table and by comparing the mass number to the atomic mass of the element in the periodic table: ^{117}Sb (For one type of decay more than one choice is correct.)

Select one or more:

Select one or more:

Select one or more:

How many α and β particles are emitted in the decay series that begins with Np-237 and finally produces the stable isotope Bi-209?

First, how many α (alpha) emissions?

First, how many α (alpha) emissions?

Second, how many β (beta) emissions?

The radioactive decay of a certain sample produced 927 disintegrations per minute. Exactly 5.00 days later, the rate of decay was found to be 546 disintegrations per minute. Calculate the half-life, in days, for the decay of this sample.

ln (Rt/Ro) = -kt

ln(546/927) = -k5

k=0.106

t1/2= 0.693/k = 6.56

By mass spectral analysis, a sample of strontium is known to contain 2.64x10^{10} atoms of Sr-90 as the only radioactive element. The absolute disintegration rate of this sample is measured as 1238 disintegrations per minute. Calculate the half-life (in years) of Sr-90.

R=KN

1238 = R(2.64e10)

k=4.689e-8

t1/2=0.693/4.7e8=14744680.9 min * 1 yr/525600 min = 28.12 yrs

How long will it take (in years) for the disintegration rate of this sample to drop to 954 disintegrations per minute?

ln(954/1238) = -4.7e-8(t)

t=5544442.166 min * 1hr/60 min * 1 day/24 hr *1 yr/ 365 day=10.5

In a living organism, the decay of C-14 produces 15.3 disintegrations per minute per gram of carbon. The half-life of C-14 is 5730 years. A bone sample with 3.7 g of carbon has 25.7 disintegrations per minute. How old is the bone sample in years?

t1/2 = 5730 yrs * 525600 min/year = 3011688000 min = 0.693/k

k=2.3e-10

ln(Rt/Ro)=-kt

25.7/3.7 = 6.954 dis/min*g

ln(6.945/15.3)=-(2.3e-10)t

3433455027*1 yr/525600 min=6532.33yrs

What percentage of the atoms of carbon in the biosphere are C-14? Hint given in feedback.

Hint, (want the number of C-14 atoms in 1 g)/(total C atoms in 1 g)x100%. Use rate = kN for number of C-14 and what you know about moles and Avogadro's number for the total number of C atoms in 1 g.

R=kN

15.3=2.3e-10(N)

N=6.65e10

1g * 1mol/12.011g * 6.022e23/1 mol = 5.01e22

%= 6.65e10/5.01e22 * 100 = 1.33e-10

There are three isotopes of phosphorus. Only one of them is stable. Calculate the binding energy per nucleon (in MeV) for P-32 (atomic mass = 31.9739 u). mass H = 1.007825 u and mass n = 1.008665 u.

# of protons = 15

15 * 1.007825 = 15.117

# of neutrons=15

15* 1.008665= 15.129975

mass defect = 30.24755-29.9783

=0.26905

0.26905 * 931.5 MeV/1 * 250.62 MeV

250.62MeV/30 = 8.354

Which isotope of P is expected to be the most stable?

Select one:

When 239Pu is used in a nuclear reactor, one of the fission events that occurs is

The atomic mass of each atom is given below its symbol in the equation. Find the energy released (in kJ) when 5.10 g of plutonium undergoes this particular fission. Hint given in feedback.

Hint, (1) Calculate the change in mass, expressed in atomic mass units, that accompanies this fission event. (2) Convert the mass loss to joules per fission. (3) Find the energy released per mole of plutonium. . .

Mass reactants-products

(1.008665+239.052)-(95.916+149.917+1.008665(4))

=240.060665-239.9

=0.193 * 1.66054e-27kg/1 = 3.2e-28 kg

E=mc^2

=(3.2e-28)(3e8)^2

=2.88e-11

2.88e-11J/atoms * 5.1 g Pu * 1mol/239 g * 6.022e23/1mol=3.7e11 J

=3.7e8 J

One of the fission products that causes major concern is Sr-90, since it is incorporated into milk and other high-calcium foods. Sr-90 undergoes beta decay with a half-life of 28.1 years. What percentage of the Sr-90 that was formed in the detonation of the first fission bombs in August 1945 is still present in the environment in August 2044?

t1/2= 0.693/k = 28.1 yr

k=0.024662

A= Ao(1/2)^n= 10(1/2)^3.523

n=(2044-1945)/28.1=3.523

A=.869

One kilogram of high-grade coal produces about 2.8 x 10^{4} kJ of energy when it is burned. Fission of one mole of U-235 releases 1.9 x 10^{10} kJ. Calculate the number of kg of coal needed to produce the same amount of energy as the fission of 1 kg of U-235 (235.05g/mol).

1 kg U * 1000 g U / 11 g U * 1 mol/235.05 g * 1.9e10kg/1mol U * 1 kg coal/2.8e4 kJ=2.89e6 kg

How many kilograms of sulfur dioxide (a major source of acid rain) are produced from the burning of the coal in question 1, if the coal is 0.76% by mass sulfur? Hint given in feedback.

Remember to use the relation between the mass of S in coal and the mass of SO_{2}.

2.89e6 kg * 0.76/100 * 100 kg SO2/50.1 kg S = 4.38e4

Gaseous diffusion is used to enrich natural uranium in U-235. Use Graham’s law (see feedback) to calculate the ratio of enrichment of U-235 by a single diffusion of UF_{6}. The atomic masses of the two principal isotopes of uranium are 235.0493 and 238.0508 for U-235 and U-238, respectively, and that of F is 18.9984. Use 4 decimal places.

Remember that the rate of effusion is proportional to the average velocity which is inversely proportional to the square root of the mass. (v_{rms>} = (3RT/M)^{0.5})

What is the ratio of enrichment of U-235 after 37 diffusions of UF6?

Your content goes here...