Questionf-block / actinoids
Which one of the following statements regarding actinoid metals is NOT correct?
- (a) The actinoid metals are usually silvery in appearance
- (b) Ionization enthalpies of the early actinoids are higher than that of the early lanthanoids
- (c) The actinoids are highly reactive metals
- (d) The actinoid metals in general show +3 oxidation state
Answer: (b) Ionization enthalpies of the early actinoids are higher than that of the early lanthanoids
(a) ✔ silvery metals. (c) ✔ highly reactive, esp. finely divided. (d) ✔ +3 is common. (b) ✘ 5f electrons are less shielded by inner core and less penetrating than 4f, so early actinoids have lower ionisation enthalpies than early lanthanoids → (b) is NOT correct.