The lab follows a sodium atom giving its valence electron to a chlorine atom, producing Na⁺ and Cl⁻. You then change the distance between the ion centers and read the Coulomb energy and force, and switch on a fragment of the rock-salt lattice to see that ionic solids are extended arrays rather than isolated pairs.
• A sodium donor, a chlorine acceptor, a transferred electron marker and a rock-salt fragment. • A separation slider from 2.4 to 6 Å and toggles for the electron transfer, the alternating lattice and explanatory particles. • Readouts: sodium charge, chlorine charge, pair Coulomb energy in eV, attractive force magnitude in nN and the transfer fraction. • Experiments: separating the ions after transfer weakens attraction and makes the energy less negative than at 2.4 Å; the lattice experiment shows an alternating extended array.
Na → Na⁺ + e⁻ and Cl + e⁻ → Cl⁻. For isolated ±e charges the energy is U = −14.3996/r eV with r in Å, and the force magnitude is 2.30708/r² nN. Energy grows less negative and force falls as separation increases.
Electron transfer is a staged illustration. The Coulomb values apply only to the completed isolated ion pair, omitting short-range repulsion, ion formation energies and lattice sums. The neutral stage displays zero ionic contribution, not zero total interaction.
They carry opposite charges, so the Coulomb force between them is attractive. The pair energy U = −14.3996/r eV becomes more negative as they approach.
No. The lattice toggle shows an alternating extended array in which each ion is surrounded by ions of opposite charge. The isolated pair is a simplification.
It falls as 1/r², and the energy becomes less negative as 1/r. At 6 Å the attraction is much weaker than at 2.4 Å.
No. Only the long-range Coulomb term for an isolated ion pair is computed. Short-range repulsion, ionization energy, electron affinity and lattice sums are outside the model.