6.4.1 Radioactivity

• Alpha decay reduces the atomic number by 2 and the mass number by 4.


  True
• The half-life of a radioactive isotope is the time it takes for half of its nuclei to decay.


  True
• What are the particles emitted in alpha decay?

  Alpha particles
• In beta-minus decay, a neutron converts into a proton, emitting an electron and an antineutrino
• In beta-minus decay, the atomic number increases by one
• What is the general nuclear equation for alpha decay?

  $^{A}_{Z}X \rightarrow ^{A - 4}_{Z - 2}Y +$$^{4}_{2}He$
• Cobalt-60 emits gamma rays after beta-minus decay
• Gamma decay involves the emission of high-energy photons.
• The mass number changes in beta-plus decay.

  False
• What is the change in atomic number during alpha decay?

  Decreases by 2
• In beta-plus decay, a proton emits a positron and a neutrino.
• Gamma decay involves the emission of high-energy photons called gamma rays.
• What is the process of radioactivity?

  Spontaneous emission of radiation
• Match each decay type with its emitted particle:

  Alpha (α) decay ↔️ Alpha particle (\( ^4_2He \))

  Beta-minus (β−) decay ↔️ Electron (e−) and antineutrino (\(\overline{ν}_e\))

  Beta-plus (β+) decay ↔️ Positron (e+) and neutrino (\(ν_e\))

  Gamma (γ) decay ↔️ Gamma ray (\( γ \))
• What happens to the atomic number in alpha decay?

  Decreases by 2
• What are the two types of beta decay?

  β− and β+
• Alpha decay involves the emission of a particle with two protons and two neutrons.


  True
• In β− decay, the atomic number increases by 1, while the mass number remains unchanged.


  True
• Gamma decay changes both the atomic and mass numbers of the nucleus.

  False
• Gamma decay is a radioactive process where an excited nucleus emits a gamma ray
• In a nuclear equation, the original nucleus is represented as ^A_ZX
• In beta-plus decay, a proton converts into a neutron, emitting a positron and a neutrino
• Beta particles are more ionizing than alpha particles.

  False
• Alpha particles can penetrate through a sheet of aluminum foil.

  False
• The half-life of an isotope is used to predict its decay
• Match the decay type with its effect on the nucleus:

  Alpha Decay ↔️ Reduces atomic number by 2

  Beta-Minus Decay ↔️ Increases atomic number by 1

  Beta-Plus Decay ↔️ Reduces atomic number by 1

  Gamma Decay ↔️ No change in atomic number
• What is radioactivity defined as?

  Spontaneous emission of radiation
• In beta-minus decay, a neutron converts into a proton, emitting an electron and an antineutrino
• The radioactive decay formula involves understanding the rate of decay and the initial number of nuclei
• The three main types of radioactive decay are alpha, beta, and gamma
• Gamma decay changes neither the atomic nor the mass number of a nucleus.


  True
• Match the decay type with its corresponding atomic number change:

  Alpha (α) ↔️ Decreases by 2

  Beta-Minus (β−) ↔️ Increases by 1

  Beta-Plus (β+) ↔️ Decreases by 1

  Gamma (γ) ↔️ No change
• Uranium-238 decays into thorium-234 by emitting an alpha particle
• Alpha decay decreases the mass number by 4.


  True
• What particle is emitted in alpha decay?

  Alpha particle
• An alpha particle is equivalent to a helium nucleus.
• Alpha decay of Uranium-238 results in Thorium-234 and an alpha particle.


  True
• What happens to the mass number in beta-minus decay?

  Remains unchanged
• The nuclear equation for gamma decay is ^A_ZX^* \rightarrow ^A_ZX + γ</latex> where γ represents the gamma ray.
• Radioactivity is a predictable process that occurs with external influence.

  False