Chemistry Revision Booklet-Final T2 Exam

Nuclear Chemistry Learning Objectives

• Describe the properties of alpha, beta, and gamma radiation.

• Write and balance nuclear reaction equations, using the symbols for protons, neutrons, electrons, positrons, alpha particles, beta particles, and gamma rays.

• Recognize a band of stability plot; predict decay types based on composition.

• Calculate half-life, radiochemical dating, and remaining amounts of radioisotopes.

• Deduce half-life from graphical representations of radioactive decay.

• Calculate nuclear binding energy in MeV.

• Compare nuclear fission and fusion.

• Differentiate nuclear reactions from chemical reactions.

Properties of Radiation

Alpha Radiation (α)

• Symbol: a

• Composition: He nuclei, He

• Charge: +2

• Mass: 6.64 × 10^-27 kg

• Energy: ~5 MeV

• Penetrating Power: Blocks by paper

Beta Radiation (β)

• Symbol: β

• Composition: Electrons

• Charge: -1

• Mass: 9.11 × 10^-31 kg

• Energy: 0.05 to 1 MeV

• Penetrating Power: Blocks by metal foil

Gamma Radiation (γ)

• Symbol: Y

• Composition: Photons

• Charge: 0

• Energy: ~1 MeV

• Penetrating Power: Not completely blocked by lead/concrete

Balancing Nuclear Reactions

• In balanced nuclear equations, mass numbers and atomic numbers on both sides must equal.

Band of Stability

• Stability depends on the ratio of neutrons to protons; this relationship is illustrated within the band of stability.

• Nuclei above the band undergo beta decay; those below undergo alpha decay or positron emission.

Half-life Calculations

• Half-life: Time for half of a radioisotope to decay. Formula: A = A₀ × (1/2)ⁿ.

• Example for calculating remaining isotope:

  • 2.000 mg over 3 half-lives results in 0.2500 mg remaining.

Nuclear Binding Energy

• Binding Energy: Energy required to break a nucleus into protons and neutrons.

• Calculated using mass defect and Einstein's equation, ΔE = Δm c².

• Example calculation for 12C using mass values and conversion to MeV.

Nuclear Fission vs Fusion

Nuclear Fission

• Splitting of heavy elements into lighter nuclei, releasing energy and neutrons; initiates a chain reaction.

Nuclear Fusion

• Combination of lighter nuclei to form a heavier nucleus, releasing energy; occurring in stars.

Differences Between Reactions

Chemical Reactions

• Involve breaking/forming bonds among valence electrons, associated with small energy changes.

• Atoms retain their identity.

Nuclear Reactions

• Involve protons/neutrons, emit radiation, and involve large energy changes, often converting one element to another.