1. Identify each statement as true or false: (a) Ionization energies are always negative quantities. (b) Oxygen has a larger first ionization energy than fluorine. (c) The second ionization energy of an atom is always greater than its first ionization energy. (d) The third ionization energy is the energy needed to ionize three electrons from a neutral atom.
2. Find three atoms in the periodic table whose ions have an electron configuration of nd7 (n= 3, 4, 5,..).
3. Arrange each of the following sets of atoms and ions, in order of increasing size: (a) Se2-, Te2-, Se; (b) Co3+, Fe2+, Fe3+; (c) Ca, Ti4+, Sc3+; (d) Be2+, Na+, Ne.