Question

part 4: practice now that you know these two types of radioactive decay, do the following:
build the first atomic nucleus show in each chain below. complete the type of decay indicated, and write in the atomic nucleus that results at each step. (these are made up decay series and do not actually occur in nature.)
fluorine-20 → (alpha ($alpha$)) → $square$ → (beta ($\beta$)) → $square$
lithium-8 → (beta ($\beta$)) → $square$ → (alpha ($alpha$)) → $square$
real - life decay of radioactive elements can be much more complicated. complete the diagram below showing the decay series of uranium - 235.
uranium - 235 ↓ (a) ↓ $square$ → (β) → $square$ ↓ (α) ↓ $square$ → (β) → $square$ ↓ (α) ↓ $square$ → (β) → $square$ ↓ (α) ↓ $square$ ↓ (α) ↓ $square$ ↓ (α) ↓ $square$ → (β) → $square$ ↓ (α) ↓ $square$ → (β) ↓ $square$
hint: your final product should be a stable isotope of lead.
(mass numbers 204, 206, 207, and 208 are stable.)

Explanation:

Step1: Recall decay particle properties

Alpha ($\alpha$) = $^4_2\text{He}$: mass number -4, atomic number -2.
Beta ($\beta^-$) = $^{\ \ 0}_{-1}e$: mass number 0, atomic number +1.

Step2: Solve Fluorine-20 chain

Fluorine (F): atomic number 9, mass 20.
Alpha decay: $^{20}_{9}\text{F}
ightarrow ^{20-4}_{9-2}\text{X} = ^{16}_{7}\text{N}$ (Nitrogen-16)
Beta decay: $^{16}_{7}\text{N}
ightarrow ^{16}_{7+1}\text{X} = ^{16}_{8}\text{O}$ (Oxygen-16)

Step3: Solve Lithium-8 chain

Lithium (Li): atomic number 3, mass 8.
Beta decay: $^{8}_{3}\text{Li}
ightarrow ^{8}_{3+1}\text{X} = ^{8}_{4}\text{Be}$ (Beryllium-8)
Alpha decay: $^{8}_{4}\text{Be}
ightarrow ^{8-4}_{4-2}\text{X} = ^{4}_{2}\text{He}$ (Helium-4)

Step4: Solve Uranium-235 series

Uranium (U): atomic number 92, mass 235.

1. Alpha decay: $^{235}_{92}\text{U}

ightarrow ^{235-4}_{92-2}\text{X} = ^{231}_{90}\text{Th}$ (Thorium-231)

1. Beta decay: $^{231}_{90}\text{Th}

ightarrow ^{231}_{90+1}\text{X} = ^{231}_{91}\text{Pa}$ (Protactinium-231)

1. Alpha decay: $^{231}_{91}\text{Pa}

ightarrow ^{231-4}_{91-2}\text{X} = ^{227}_{89}\text{Ac}$ (Actinium-227)

1. Beta decay: $^{227}_{89}\text{Ac}

ightarrow ^{227}_{89+1}\text{X} = ^{227}_{90}\text{Th}$ (Thorium-227)

1. Alpha decay: $^{227}_{90}\text{Th}

ightarrow ^{227-4}_{90-2}\text{X} = ^{223}_{88}\text{Ra}$ (Radium-223)

1. Alpha decay: $^{223}_{88}\text{Ra}

ightarrow ^{223-4}_{88-2}\text{X} = ^{219}_{86}\text{Rn}$ (Radon-219)

1. Alpha decay: $^{219}_{86}\text{Rn}

ightarrow ^{219-4}_{86-2}\text{X} = ^{215}_{84}\text{Po}$ (Polonium-215)

1. Alpha decay: $^{215}_{84}\text{Po}

ightarrow ^{215-4}_{84-2}\text{X} = ^{211}_{82}\text{Pb}$ (Lead-211)

1. Beta decay: $^{211}_{82}\text{Pb}

ightarrow ^{211}_{82+1}\text{X} = ^{211}_{83}\text{Bi}$ (Bismuth-211)

1. Alpha decay: $^{211}_{83}\text{Bi}

ightarrow ^{211-4}_{83-2}\text{X} = ^{207}_{81}\text{Tl}$ (Thallium-207)

1. Beta decay: $^{207}_{81}\text{Tl}

ightarrow ^{207}_{81+1}\text{X} = ^{207}_{82}\text{Pb}$ (Lead-207, stable)

Answer:

1. First Decay Chain:

• Fluorine-20 → alpha (α) → Nitrogen-16
• Nitrogen-16 → beta (β) → Oxygen-16

1. Second Decay Chain:

• Lithium-8 → beta (β) → Beryllium-8
• Beryllium-8 → alpha (α) → Helium-4

1. Uranium-235 Decay Series:

• Uranium-235 → α → Thorium-231
• Thorium-231 → β → Protactinium-231
• Protactinium-231 → α → Actinium-227
• Actinium-227 → β → Thorium-227
• Thorium-227 → α → Radium-223
• Radium-223 → α → Radon-219
• Radon-219 → α → Polonium-215
• Polonium-215 → α → Lead-211
• Lead-211 → β → Bismuth-211
• Bismuth-211 → α → Thallium-207
• Thallium-207 → β → Lead-207