NUCLEAR CHEMISTRY

FACT!1. A Transmutation is any alteration in the

nucleus2. There are no stable isotopes above

element #831. Elements that are unstable will emit energy in the

form of Radiation2. Called Radioisotopes

3. Stability is based on the P:N Ratio

TYPES OF PARTICLES THAT ARE EMITTED

ParticleType

Symbol Mass Charge Penetrating

Power

Alpha 2He4 α 4 2 Low

Beta -1e0 , β- 0 -1 Moderate

Positron +1e0 , β+

0 +1 Moderate

Gamma 0γ0 0 0 HighX-ray

The Effects of an Electric field on Charged Particles

2 TYPES OF TRANSMUTATIONS

1. Natural

Artificial

A type of Decay that occurs naturally therefore you will see only 1 reacting nuclei that will undergo a change

1. Alpha ( )Decay2. Beta ( )Decay3. Positron ( ) emission4. Gamma ( ) decay

A type of Decay that does not occur naturally, therefore you will see 2 nuclei reacting

2 Types1. Fusion2. Fission

NATURAL DECAYAND WRITING NUCLEAR EQUATIONS

Alpha

Notice several things about it: 1) The atom on the left side is the one that splits into two pieces. 2) One of the two atoms on the right is ALWAYS an alpha particle.3) The other atom on the right ALWAYS goes down by two in the atomic number and four in the mass number.

MORE EXAMPLES OF ALPHA DECAY

MORE EXAMPLES OF ALPHA DECAY

Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides. Then click the link to see the answers.

Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides. Then click the link to see the answers.

Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side. OK, write the alpha decay equations for these five nuclides.

BETA DECAY AND WRITING EQUATIONS

BETA DECAY PRACTICEHere's your first set of exercises. Write out the full beta decay equation. Then click the link to see the answers.

BETA DECAY PRACTICEHere's your first set of exercises. Write out the full beta decay equation. Then click the link to see the answers.

POSITRON EMISSION B+, +1E0

-1e0 + 19K37 ------> 18Ar37

Side Note:K Capture (capture and

electron) yields the same results

19K37 ------> +1e0 + 18Ar37

PET SCAN (POSITRON EMISSION)

GAMMA DECAY No change in Mass or

Charge

ARTIFICIAL DECAYTHE CONVERSION OF MATTER INTO

ENERGYFusion Fission

A reaction where 2 lite nuclei (alike) are joined together to make a heavier nuclei.

Ex: Reactions on the Sun Good: Yields A lot of

Energy Bad: Requires a lot of

energy to run Fuse 2 like nuclei (repel) Need particle accelerators

to inc. KE Synchroton Cyclotron

The splitting of heavy nuclei (bombard with high energy Neutrons 0N1) into a smaller nuclei

Good: Yields a lot of energy

Bad: Produces a lot of Radioactive waste (disposal issues and half life)

FUSION

1H1 + 1H1 -----> 1H2 + +1e0 + energy1H1 + 1H2 -------> 2He3

FISSION0n1 + 92U235 ------> 56Ba142 + 36Kr91 + 3 0n1 + ENERGY0n1 + 92U235 ------> 54Xe143 + 38Sr90 + 3 0n1 + ENERGY

HALF-LIFEThe time that it takes for a substance

(radioactive) to lose ½ its mass.A. Determine the Age of rocks

(Carbon Dating)

During Half-Life ProblemsRemember:1. the longer the half-life, the SLOWER

the decay (Dangerous)2. The shorter the half-life, the faster the

decay(used in medicine)

CALCULATING THE HALF-LIFE

You will need to know 5 things1. Total time2. ½ life time3. # of half life4. Initial Mass5. Final Mass

If starting with Initial Mass

If asked what fraction remains?

Always start with (1)

128g

64g

32g

16g

8g

4g

2g

1g

1

2

3

4

5

6

7

# of Half lifes

1

1/2

1/4

1/8

1/16

1

2

3

4

# of Half lifes

HALF-LIFE

Total Time½ life time=# of

½ lifes#

Initial Mass

Final Mass2

2

1) The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed? 12.5g remaining

2) Os-182 has a half-life of 21.5 hours. How many grams of a 10.0 gram sample would have decayed after exactly three half-lives?

8.75g decayed, 1.25g remain

3) At time zero, there are 10.0 grams of W-187. If the half-life is 23.9 hours, how much will be present at the end of one day? Two days? Seven days?

1 day = 5.00g, 2 days = 2.50g, 7 days = .078g

USES OF RADIOISOTOPES Carbon Dating – C14 no longer taken in

by a dead organism Ratio of U238/Pb206 to date rocks I131 – used to study thyroid conditions Co60 – emits large amounts of gamma

radiation. Used in treating cancers like Prostate

Co60 and Cs137 – emit gamma rays, used to kill Anthrax Bacilli

Tc43 –used to treat cancerous tumors, absorbed by cancer cells