Organic Chemistry: Atomic Structure

Problems: Ions and Ionic Bonding

Problem : When several electrons are removed from an atom, the energy that it takes to remove the first electron is the first ionization energy, the energy it takes to remove the second electron is the second ionization energy, and so on.

(a) In general the second ionization energy is much greater in magnitude than the first ionization energy. Explain why this is so.

(b) Consider the following IE (ionization energy) data for lithium and beryllium. Explain why there is such a large jump between the first and second ionization energies of Lithium.

(a) The difference is due to shielding. The first electron is shielded by one more electron than the second and is therefore easier to remove.

(b) The first ionization of Lithium removes a valence electron, but the second ionization removes an inner electron, depriving lithium of an octet. Both ionizations of beryllium remove valence electrons.

Problem : Calculate the energy change of the following reaction (in eV (electron volts) with the provided energy data:

Energy Change = IE1(Mg) + IE2(Mg) + 2 * EA(Cl) = +15.45 eV This reaction is unfavorable because of the gain in energy. However, here we have neglected the electrostatic attractions that would result between the magnesium and chloride ions and would contribute stabilizing negative energy.