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Potential Energy Diagrams For Formation Of Bonds

Show/Hide Lessons (Solid State Physics | H3 Physics)
  1. Types Of Bonds
  2. Potential Energy Diagram For Formation Of Bonds
  3. Potential Energy Diagram For The Formation Of a Van Der Waals' Bond
  4. Crystal Structure
  5. Close-packed Structures
  6. Hexagonal Close-packed Structure
  7. Drude Model Of Electrical Conduction
  8. Number Density Of Free Electrons
  9. Free Electron Theory Of Solids
  10. Current Density
  11. Resistance And Resistivity
  12. Temperature Dependence Of Resistivity
  13. Fermi-Dirac Statistics
  14. Fermi Level And Fermi Energy
  15. Fermi Function
  16. Energy Band Structures In Solids
  17. Electrical Conductivities Of Materials
  18. Zener Diode
  19. Hall Effect
  20. Electrical Characteristics Of Commercial Alloys

Potential Energy Diagram For The Formation Of A Covalent Bond

Bond potential and equilibrium separationPotential energy rises steeply at very small separation, reaches a deep minimum at equilibrium separation r zero, and approaches zero at large separation.rUr₀
The minimum gives the equilibrium separation. Its large depth is the binding energy.

Explanation for the graph: Consider the formation of a H2 molecule. The potential energy of one H atom in the presence of the other is plotted in the figure. As the atoms approach one another, the electrons concentrate between the nuclei, and attraction occurs. Hence, the potential energy, U, decreases. At very short distances, the electrons would be ‘squeezed out’. As a result, the two positively charged nuclei will experience a repulsive force due to the other. This results in the curve rising as r decreases further. At ro, the energy between the atoms is the lowest. This is point of greatest stability for the molecule. Hence, ro, known as the equilibrium spacing of atoms, gives the average separation of the atoms in the molecule. Electrostatic force at equilibriunm separation is 0. The depth of the well gives the dissociation (or binding) energy of the molecule. This is how much energy that must be put into the system to separate the atoms into infinity, where the potential energy is zero. An approximation to the potential energy in the vicinity of the equilibrium spacing is U =; - A/rm + B/rⁿ ,where A and B are constants associated with the attractive and repulsive parts of the potential energy respectively m and n are small integers. (For ionic and some covalent bonds, the attractive term is often written with m=1) r is the separation distance.

Potential Energy Diagram For The Formation Of An Ionic Bond

Potential-energy barrier and bonded minimumPotential energy rises over an activation barrier before falling to a stable bonded minimum, then approaches zero at large separation.rUr₀activation barrier
The barrier is the activation energy; the minimum marks the stable bonded separation.

The point of greatest stability is ro, which gives the equilibrium spacing of the atoms. However, as the atoms approach each other from a large distance, the force is initially repulsive rather than attractive. The atoms require some additional energy, known as activation energy, to be injected into the system in order to overcome the potential barrier between them. Only then will bonds start to form. Note: The activation energy often reflects a need to break other bonds, before the one under discussion can be made. For example, oxygen (O2) and hydrogen (H2) molecules must be broken into their atoms (O and H) before they can combine to form water (H2O) molecules. The activation energy represents the amount of energy input to break up the O2 and H2 moleculoes. When the atoms combine, there will be a release of energy, much larger than what was put in initially. Oftern, this release of energy provides for the activation energy for further reaction.

Potential Energy Diagram For The Formation Of a Van Der Waals’ Bond

Shallow van der Waals potential wellPotential energy rises steeply at very small separation, reaches a shallow minimum at equilibrium separation r zero, and approaches zero at large separation.rUr₀
The minimum gives the equilibrium separation. Its small depth is the binding energy.

The potential energy of a Van der Waals’ bond has the same general shape as that of a covalent bond. However, the binding energy would be much smaller. Back To Solid State Physics

8. Practice, Quiz and Next Step

Close your notes and use Potential Energy Diagrams For Formation Of Bonds in the supplied context below. This requires a constructed explanation or working, not recognition of an option.

Fresh context: An unfamiliar data set or physical system requires you to apply Potential Energy Diagrams For Formation Of Bonds while stating the model, regime and assumptions.

  1. Retrieve: define potential energy diagrams for formation of bonds in your own words, including units, sign or conditions where relevant.
  2. Represent: Choose and label an appropriate diagram, graph, table or symbolic model; derive or justify the relationship used.
  3. Apply: Reach a conclusion, then evaluate it using units, uncertainty, a limiting case and one practical or modelling limitation.

Check the response before looking back

  • The model, regime, coordinates and assumptions are explicit.
  • The derivation or multi-step reasoning is visible rather than implied.
  • The conclusion is tested against units, data quality and a limiting case.
  • A practical control, uncertainty or model limitation is evaluated where applicable.

If one check fails, name that exact gap, revisit the matching explanation or worked example, and redo the task with different values or a different situation. Then use theH3 Physics course hub orpractice browser for an independent re-test.

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