Answer: B
The photoelectric effect is the emission of electrons from the surface of a metal when light
shines on it. Electrons are emitted, however, only when the frequency of that light is greater
than a certain threshold value characteristic of the particular metal. The alkali metals, with only
one electron in their valence shells, have the lowest threshold values.
- The lithium ion and the hydride ion are isoelectronic. Which of the following statements
is true of these two chemical species in the ground state?
A. Li+is a better reducing agent than H–.
B. The H–ion is several times larger than the Li+ion.
C. It requires more energy to remove an electron from H–than from Li+.
D. The chemical properties of the two ions must be the same because they have the
same electronic structure.
E. None of these is a true statement.Answer: B
Both the lithium ion, Li+, and the hydride ion, H–, have the configuration 1s^2. Both species have
2 electrons, but the lithium ion has 3 protons, which cause a greater “pull” on the 2 electrons
than the 1 proton found in the hydride ion.
- Which of the following configurations represents a neutral transition element?
A. 1 s^22 s^22 p^2
B. 1 s^22 s^22 p^63 s^23 p^4
C. 1 s^22 s^23 s^2
D. 1 s^22 s^22 p^63 s^23 p^63 d^84 s^2
E. 1 s^22 s^22 p^63 s^23 p^63 d^104 s^24 p^6Answer: D
The transition elements are filling the dorbitals. When completely filled, the d orbitals hold a
maximum of 10 electrons.
Part II: Specific Topics