|Matters and Properties of Matters|
|Atomic Structure with Examples|
|The Mole Concept with Examples|
|Gases with Examples|
|Chemical Reactions with Examples|
|Nuclear Chemistry (Radioactivity)|
|--Natural Nuclear Reactions and Radioactive Decays|
|--Artificial Radioactivity Fission and Fusion|
|--Half Life and Radioactive Decay Rates|
|--Nuclear Chemistry (Radioactivity) Cheat Sheet|
|Acids and Bases|
|Rates of Reactions (Chemical Kinetics)|
|Exams and Problem Solutions|
Natural Nuclear Reactions and Radioactive Decays
In radioactive reactions, charge and mas number are conserved. Now we explain radioactive decays, radiation one by one.
1. Alpha Decay (Radiation):
Alpha (α) particles can be called Helium-4 nuclei (24He+2). After alpha decay, atomic number of nucleus decreases by 2 and mass number decreases by 4 and number of neutrons also decreases by 2.
92238U → 90234Th + 24He
86222Rn → 84218Po + 24He
Properties of α particles:
2. Beta Decay (Radiation):
Beta radiation is formed during conversion of one neutron to one proton. Particle produced after this process is electron. We show it in nuclear reactions with Greek letter "β-"
01n → 11p + -10e(β-)
After beta decay, number of proton increases by one and number of neutrons decreases by one. Thus, mass number stays constant.
55137Cs → 56137Ba + -10e
13H → 23He + -10e
614C → 714N + --10e
Properties of beta particles:
3. Positron Decay (Radiation):
It is also called, beta positive decay. It is denoted by +10e or β+. Positron decay is conversion of one proton to one neutron.
11p → 01n + +10e
In positron decay mass number is conserved, however, number of protons decreases by one and number of neutrons increases by one.
1938K → 1838Ar + +10e
53122I → 52122Te + +10e
2754Co → 2654Fe + +10e
Properties of positron particles:
4. Gamma Decay (Radiation):
Gamma radiations are short wave length electromagnetic waves. Gamma decays occur after other radiations to emit excess energy of nucleus to become stable. Gamma radiation is shown with "γ".
In reactions it is shown as "00γ". After gamma decay, atomic number and mass number of nucleus are conserved.
1st step: 94240Pu → [92236U] +24He
2nd step: 92236U → 92236U + 00γ
Properties of gamma rays:
5. Electron Capture:
Some of nuclei capture one electron on inner shell of it. This electron convert one proton to one neutron in nucleus.
11p + -10e → 01n
After electron capture, mass number is conserved, atomic number decreases by one and number of neutrons increases by 1.
2758Co + -10e → 2658Fe
47106Ag + -10e → 46106Pd
90234X + β- → Y + γ + 2β+ + α
Find number of protons and mass number of Y in given reaction above.
Number of protons in left side of reaction is;
Thus, number of protons in right side of reaction must be 89.
Y+1.(0) + 2.(+1) +2 =89
Y=85 number of protons
Mass number of reactants must be equal to mass numbers of products.
234+0=234 mass number of reactants
Y+ 1.(0) + 2.(0) + 4=234
Y + 4=234
Y=230 mass number of Y
Example: X does nuclear decays and converted to Y. Graph given below shows changes in the mass number vs atomic number of X.
Which ones of the following statements are true?
I. X does 2 α and 4 β- decays
II. X and Y are isotopes
III. Neutron numbers of Y is 126
In β- decay mass number stays constant and atomic number increases by 1. In α decay mass number decreases by 4 and atomic number decreases by 2.
I. As shown in the graph, X does 2 α and 4 β- decays I is true
II. We see that in graph X and Y has same atomic number so they are isotopes. II is true
III. In graph, we see atomic number of Y is 84 and mass number is 210
210-84=126 neutrons III is true.