Which of the following statements is(are) true?
a. F has a larger first ionization energy than does Li.
b. Cations are larger than their parent atoms.
c. The removal of the first electron from a lithium atom (electron configuration is 1s2 2s1) is exothermic—that is, removing this electron gives off energy.
d. The He atom is larger than the H+ ion.
e. The Al atom is smaller than the Li atom.