Answer: D
The electron configuration for the Co3+ion is ls^22 s^22 p^63 s^23 p^63 d^6. If you missed this, review
electron configurations of transitional metals. The Co3+ion would have a total of 24 electrons:
10 pairs of electrons and four unpaired electrons in the 3dorbitals. Atoms in which one or
more electrons are unpaired are paramagnetic.
- Which of the following series of elements is listed in order of increasing atomic radius?
A. Na, Mg, Al, Si
B. C, N O, F
C. O, S, Se, Te
D. I, Br, Cl, F
E. K, Kr, O, AuAnswer: C
Atomic radius increases as one moves down a column (or group).
- A characteristic that is unique to the alkali metals is
A. Their metallic character
B. The increase in atomic radius with increasing atomic number
C. The decrease in ionization energy with increasing atomic number
D. The noble gas electron configuration of the singly charged positive ion
E. None of these answer choices is correct.Answer: D
The word unique in this question means that only the alkali metals possess this particular
characteristic. Of the choices listed, D is the only property that is unique to the alkali metals.
- Which of the following elements most readily shows the photoelectric effect?
A. Noble gases
B. Alkali metals
C. Halogen elements
D. Transition metals
E. The chalcogen familyElectronic Structure of Atoms