For a particular multi-electron atom, application of the variational approach using an effective nuclear charge parameter Z 0 results in the following expression for E(Z 0 ), where a is a constant and energy is in atomic units (Hartree): E(Z 0 ) = −Z 0 e −aZ0 Determine the variational parameter Z 0 and the (minimum) variational energy.

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.

The radius of an atom is closest in size to a

He latent heat of vaporization for ethyl alcohol is 854 j/g. the amount of energy, rounded to the nearest whole number, needed to change 5.20 grams of ethyl alcohol from a liquid to a gas is