(455) Binding energy per nucleon [IB Physics SL/HL]

Binding Energy per Nucleon

• Definition: Energy released when an atom is formed from its constituent parts.

• Nucleons: Sum of protons and neutrons in an atom.

• Graph Overview:

  • Y-axis: Binding energy per nucleon.

  • X-axis: Nucleon number (hydrogen = 1, helium = 2, etc.).

  • Shape: Rises, peaks at iron (Fe-56), then declines.

Key Concepts

• Peak Binding Energy:

  • Occurs at iron (26th element, Fe-56).

  • Represents the maximum stability of nucleons in an atom.

• Fusion vs. Fission:

  • Fusion:

    • Combines lighter elements into heavier ones (e.g., hydrogen to helium).

    • Requires energy to increase binding energy per nucleon, moves right on the curve.

  • Fission:

    • Splits heavier elements into lighter ones (e.g., uranium).

    • Moves left on the curve, which also increases binding energy.

Stellar Processes

• Hydrogen Fusion:

  • Stars naturally fuse hydrogen into helium, generating energy.

  • Can only fuse until reaching iron in the core.

• Collapse and Supernova:

  • When a star has iron in its core, it cannot fuse further, leading to gravitational collapse.

  • This collapse results in a supernova explosion, which can create new elements heavier than iron.

Nucleosynthesis

• Formation of Elements:

  • Stars are responsible for creating elements through nucleosynthesis until iron.

  • Elements heavier than iron produced during supernova explosions.

Interesting Note

• The iron in your blood is the same element that signals the end of stellar fusion in a massive star, leading to their dramatic collapse and explosion.