August Homework

AUGUST HOMEWORK SET #3                   Name:

CHAPTER 3 – Nuclear Chemistry

Chapter 3 Book Assignments:  52 pts

Assignment:	Due Date	Your pts/total
Read pages 119-130
Outline Ch 3:  nuclear chemistry		/10
Answer exercise 3.1 page 122		/5
Answer example 3.1 and 3.2 page 127		/5
Answer example 3.3 page 128		/2
Answer Block’s summary sheet		/30

Chapter 3 Homework Assignments: 87 pts 

Assignment:	Your pts/total
Natural and Artificial Radioisotopes List	/19
AP Nuclear Example Problems	/30
AP Practice exercises #1-14 pages 131-133	/14
AP free-response page 133	/10
Crib Notes	/14

TOTAL POINTS:        /139 pts

Block’s Summary Sheet:  Chapter 3:  Nuclear Chemistry  30 pts

1.      List the five subatomic particles with their symbols, representations, masses, and charges. (10 pts)

2.    Define and distinguish between the gamma and x-ray. (3 pts)

3.    Give 4 verbs indicating the particle goes on the product side after the yields arrow and the 4 verbs indicating it goes on the reactant side. (7 pts)

4.    What are the “naturally radioactive” elements? (1)

5.    What are the “transuranium” elements? (1)

6.    What does “dps” stand for? (1)

7.    Give the formula for the rate of radioactive decay and note on formula sheet.  What do the variables stand for? (3)

8.    What is “critical mass”? (1)

9.    List 2 ways to moderate a fission reaction. (2)

10.  List the fusion reaction. (1)

AP Nuclear Example Problems                                Name:

30 points

1.  Uranium-238 decays by alpha emission.  Write a balanced equation for this nuclear decay: (3 pts)

2.  Bromine-82 decays by beta emission.  Write a balanced equation for this nuclear reaction: (3 pts)

3.  Oxygen-15 decays by positron emission.  Write a balanced equation for this nuclear reaction: (3 pts)

4.  Potassium-40 captures an electron. Write a balanced equation for this nuclear reaction:

(3 pts)

5.  Phosphorus-32 is a radioactive isotope that has a half-life of 14.28 days and is used in treating leukemia patients.  Starting with 45.0 grams of P-32, how many grams would be left after 35.0 days? (5 pts)  SHOW THE FORMULA YOU WILL USE:

9.  Fission:  Uranium-235 is hit with a neutron to produce strontium-90,  xenon 143, and three neutrons.  Write the equation here:

6.  Fusion:  when 2 HYDROGEN nuclei (tritium H-3 and deuterium H-2) combine to produce a HELIUM He-4 nucleus, a neutron, and lots of ENERGY.  Write the equation here: (3 pts)

7.  Consider C-14- predict what type of decay will occur, giving a reason and the equation. 

(3 pts)

Type of Decay:

Reason:

Equation:

8.  Consider C-11- predict what type of decay will occur, giving a reason and the equation. 

(3 pts)

Type of Decay:

Reason:

Equation:

9.  What type of decay will occur for Bi-189?  WHY? (2 pts)

10.  What type of decay will occur for Cf – 252?  WHY? (2 pts)

Crib Notes Ch 3 – NUCLEAR Chemistry                  Name:

14 pts

Types of nuclear decay:

1.  Alpha emission:  loses 4 mass, loses 2 number, produces a helium nucleus (helium atom without the 2 electrons, which makes it charged)

4 He

2

2.  Beta emission:  mass stays the same, gains one atomic number, produces an “electron”

 0

-1 e^-

3.  positron emission:  mass stays the same, atomic number goes down by one, produces a positron

0

           +1 e⁺

4.  electron capture:  usually a 1s electron is captured as it is closest to the nucleus, mass stays the same, atomic number goes down by one, add an electron to the reactant side, produces energy (hv)

0

            -1 e^-

5.  gamma rays:  similar to x-rays having no charge and not mass, the nucleus loses energy during gamma ray emission, travel at the speed of light, great penetrating power, but less ionizing power than a beta particle…

Penetrating power:  alpha< beta < neutron < gamma      neutron = _________ ?

HALF-LIFE:

Half-life is a first order kinetics reaction meaning that the rate of reaction is proportional to the concentration of one of the reactants

N = N_o (1/2)^T/H                                             ln (N_o ) = kt

                                                                                N

N = amount left in grams

N_o = initial amount in grams

T = total time

H = half-life

t _½ = 0.693      k = rate constant

              k

Predicting stability and what type of decay an isotope will undergo:

1.  elements with atomic # > 60 undergo alpha decay (check the isotope’s mass though***)

2.  elements with atomic # > 90 undergo spontaneous fission  (= neutrons given off)

3.  Calculating stability using neutron to proton ratio:

                                   

                                    (atomic mass – atomic number)

                                                atomic number

4.  usually, the lower the ratio (closer to one), the more stable the isotope

5.  elements less than 83 are more stable than those beyond Bi

6.  compare the isotope’s mass with the “normal” mass off the Periodic Table – the

normal mass is more stable              

                                                             

a.  if the isotope’s mass < normal

- positron emission if the mass is “light”

- electron capture if the mass is “heavy”

b.  if the isotope’s mass > normal, electron (beta) emission *** common

7. nuclei with an even number of protons or neutrons tend to be more stable than

those with an odd number WHEN comparing two elements close together

8.  Certain numbers of protons and neutrons appear to be VERY stable magic

Numbers:  2,8,20,28,50,82,126

Answer the following about fission and fusion (14 pts):

FISSION of U-235:

1.  U-235 and a neutron produce Br-87 and La– 146 and 3 neutrons:

2.  U-235 and a neutron produce Ba-139 and Kr-94 and 3 neutrons:

FUSION:  tritium and deuterium yield a helium atom and a neutron:

Natural and Artificial Radioisotopes List            Name:

19 points

Name of isotope:	Use of isotope:
Rn-222 (natural) p.124
Ra-226 (natural) p.124
U-238 (natural) p.124
K-40 (natural) p.124
H-3
C-11
C-14
Na-24
P-32
Cr-51
Co-57
Fe-59
Co-60
I-131
Gd-153
Ra-226
U-235
Ir-192
Am-241