Name ______________________ Date _______________________

© 2003 Teachnology, Inc. 15

Nuclear Chemistry: Identifying Forms of Radiation Nuclear reactions are quite different than chemical reactions in that they involve a change inside the nucleus rather than an exchange or sharing of electrons. An unstable nucleus decays into a products that are more stable. When an unstable nucleus decays, it releases radiation in the form of alpha particles, beta particles, and/or positrons.

Alpha Decay: 94239

Pu 92235

U + 24

He

Beta Decay: 2760

Co 2860

Ni + 1

0−

β

Positron Emission: 2037

Ca 1937

K + 1

0+

β

Directions: Place a check to identify the form of radiation demonstrated by each reaction below.

Alpha Beta Positron 1.

91234

Pa 92234

U + 1

0−

β

2.

86222

Rn 84218

Po + 24

He

3.

1937

K 1837

Ar + 1

0+

β

4.

4399

Tc 4499 Ru +

10−

β

5.

1019

Ne 919

F + 1

0+

β

6.

1532

P 1632 S +

10−

β

7.

92238

U 90234

Th + 24

He

8.

2653

Fe 2553

Mn + 1

0+

β

9.

87220

Fr 85216

At + 24

He

Name ______________________ Date _______________________

© 2003 Teachnology, Inc. 16

Nuclear Chemistry: Predicting Nuclear Decay Part 1 Directions: Predict the products of the following nuclear reactions.

1. 235 U

231 Th + ________________

2. 36 Li +

01 n

24

He + ________________

3. 614C

714

N + ________________

4. 226 Ra

222 Rn + ________________

5. 32P +

10−

e ________________

6. 87220 Fr +

24

He ________________

7. 198Au

198 Hg + ________________

8. 714

N + 24

He 11

H + ________________

Name ______________________ Date _______________________

© 2003 Teachnology, Inc. 17

Nuclear Chemistry: Predicting Nuclear Decay Part 2 Directions: Predict the reactants of the following nuclear reactions.

1. ________________ 231

Th + 24

He

2. ________________ 1

0−

e + 54131

Xe

3. ________________ + 24

He 241

Pu + 01 n

4. ________________ 1

0−

e + 510B

5. 7 Li + ________________

48 Be

6. 235 U + ________________

72 Zn + 4

01 n +

62160Sm

7. ________________ 1

0−

e + 3He

8. ________________ 85216

At + 24

He

Name ______________________ Date _______________________

© 2003 Teachnology, Inc. 18

Nuclear Chemistry: Half-life

Radioactive substances decay at a constant rate. There are a number of unstable nuclei that decay in a given time. The time that it takes for half of the atoms in a given sample of an element to decay is termed the half-life. To determine half-life: Half-life = total time elapsed

half-life

To determine how much of an unstable remains after a given time:

Fraction remaining= (1/2)Half-life Data Table 1: Known Half-life of selected elements: 198Au: 2.69 days 131I: 8.07 days 42K: 12.4 hours 32P: 14.3 days 90Sr: 28.1 years 53Fe: 8.51 minutes 1. Predict the mass of a 75.00 g sample of 198Au after 16.14 years. 2. How many days are required for 32P to undergo 6 half-lives? 3. Predict the mass of a 125.00 g sample of 42K after 62.0 years. 4. Of all of the elements listed above, which element decays the fastest? Predict the mass of a 107g sample of this element after 34.04 minutes. 5. If a 120 g sample of a radioactive element decays to 15 g in 40 minutes, what is the element’s half-life?

Name ______________________ Date _______________________

© 2003 Teachnology, Inc. 19

Nuclear Chemistry Review Quiz: Form A

Directions (Questions 1 and 2): For questions 1 and 2 predict the missing reactant or product and identify the form of radiation demonstrated in each problem.

1. 198Au

198 Hg + ________________

Form of radiation: __________________

2. 238

U + ________________ 241

Pu + 01 n

Form of radiation: __________________

3. Predict the mass of a 135 gram sample 85

Kr after 32.28 years.

85

Kr Half-life = 10.76 years

---------------------------------------------------------------------------------------------------------- Nuclear Chemistry Review Quiz: Form B

Directions (Questions 1 and 2): For questions 1 and 2 predict the missing reactant or product and identify the form of radiation demonstrated in each problem.

1. 614C

714

N + ________________

Form of radiation: __________________

2. ________________ 1

0−

e + 3He

Form of radiation: __________________

3. Predict the mass of a 155 gram sample 32

P after 28.6 days.

32

P Half-life = 14.3 days