8.1 Radioactivity

• What is radioactivity?

  Emission from unstable nuclei
• Match the type of radioactive decay with its emission:

  Alpha decay ↔️ Alpha particle

  Beta decay ↔️ Electron

  Gamma decay ↔️ Gamma ray
• What material can stop beta radiation?

  Aluminum foil
• In beta decay, an electron and an antineutrino are emitted.
• Match the decay type with its effect on the nucleus:

  Alpha decay ↔️ Atomic number decreases by 2, mass number decreases by 4

  Beta decay (electron emission) ↔️ Atomic number increases by 1, mass number unchanged

  Beta decay (positron emission) ↔️ Atomic number decreases by 1, mass number unchanged

  Gamma decay ↔️ Atomic number and mass number unchanged
• In beta decay (electron emission), the atomic number increases by 1
• Match the decay type with its equation change:

  Alpha Decay ↔️ $_{Z}^{A}\text{X} \rightarrow _{Z - 2}^{A - 4}\text{Y} +$$_{2}^{4}\text{He}$

  Beta Decay (positron emission) ↔️ $_{Z}^{A}\text{X} \rightarrow _{Z - 1}^{A}\text{Y} +$$_{ + 1}^{0}e +$$\nu_{e}$

  Gamma Decay ↔️ $_{Z}^{A}\text{X}^ *$$\rightarrow _{Z}^{A}\text{X} +$$\gamma$
• In beta decay (electron emission), the mass number remains unchanged.


  True
• Radioactivity involves unstable nuclei emitting particles or radiation to become more stable.


  True
• All radioactive decays involve the spontaneous emission of particles or radiation.


  True
• Gamma radiation is deflected in a magnetic field.

  False
• In beta decay (electron emission), the atomic number increases by 1
• In beta decay (electron emission), an antineutrino is emitted.


  True
• During alpha decay, the mass number decreases by 4.


  True
• In beta decay (positron emission), the mass number remains constant.


  True
• Match the decay type with its general equation:

  Alpha Decay ↔️ <tex>$_{Z}^{A}\text{X} \rightarrow _{Z - 2}^{A - 4}\text{Y} +$$_{2}^{4}\text{He}$</tex>

  Beta Decay (electron emission) ↔️ <tex>$_{Z}^{A}\text{X} \rightarrow _{Z + 1}^{A}\text{Y} +$$_{ - 1}^{0}e +$$\overline{\nu}_{e}$</tex>

  Beta Decay (positron emission) ↔️ <tex>$_{Z}^{A}\text{X} \rightarrow _{Z - 1}^{A}\text{Y} +$$_{ + 1}^{0}e +$$\nu_{e}$</tex>

  Gamma Decay ↔️ <tex>$_{Z}^{A}\text{X}^ *$$\rightarrow _{Z}^{A}\text{X} +$$\gamma$</tex>
• What is the use of technetium-99m in medical imaging?

  Diagnose health conditions
• Lead is a commonly used material for radiation shielding.


  True
• Radioactivity is the process by which unstable nuclei spontaneously emit particles or electromagnetic radiation in order to become more stable
• Radioactivity is the process by which unstable nuclei spontaneously emit particles or radiation to become more stable
• Gamma radiation is highly ionizing but has low penetration power.

  False
• What remains unchanged during gamma decay?

  Atomic and mass number
• Which particle is emitted during beta decay to conserve lepton number?

  Antineutrino
• In beta decay (positron emission), the atomic number increases by 1.

  False
• What is emitted in beta decay (positron emission)?

  Positron and neutrino
• What are the particles emitted in beta decay (positron emission)?

  Positron and neutrino
• What are the three main types of radioactive decay?

  Alpha, beta, gamma
• Match the decay type with its effect on the nucleus:

  Alpha Decay ↔️ Atomic number decreases by 2, mass number decreases by 4

  Beta Decay ↔️ Atomic number increases by 1, mass number remains the same

  Gamma Decay ↔️ No change in atomic or mass number
• What is the general equation for alpha decay?

  $_{Z}^{A}\text{X} \rightarrow _{Z - 2}^{A - 4}\text{Y} +$$_{2}^{4}\text{He}$
• What is emitted in gamma decay?

  Gamma photon
• What particle is emitted during alpha decay?

  Alpha particle
• What particles are emitted during beta decay (electron emission)?

  Electron and antineutrino
• What particle is emitted during gamma decay?

  Gamma photon
• What is half-life defined as?

  Time for half nuclei to decay
• The number of nuclei remaining after time t in radioactive decay is given by <tex>$N(t) =$$N_{0} e^{ - λt}$</tex>.


  True
• Americium-241 is used in smoke detectors to detect smoke
• Why is minimizing exposure time important in radioactivity safety?

  Reduces radiation dose
• In alpha decay, the atomic number decreases by 2 and the mass number decreases by 4.

  True
• Order the three types of radioactive decay based on their ability to penetrate matter.

  1️⃣ Alpha decay

  2️⃣ Beta decay

  3️⃣ Gamma decay
• Match the decay type with its general nuclear equation:

  Alpha decay ↔️ $_{Z}^{A}\text{X} \rightarrow _{Z - 2}^{A - 4}\text{Y} +$$_{2}^{4}\text{He}$

  Beta decay (electron emission) ↔️ $_{Z}^{A}\text{X} \rightarrow _{Z + 1}^{A}\text{Y} +$$_{ - 1}^{0}e +$$\overline{\nu}_{e}$

  Beta decay (positron emission) ↔️ $_{Z}^{A}\text{X} \rightarrow _{Z - 1}^{A}\text{Y} +$$_{ + 1}^{0}e +$$\nu_{e}$