Spectroscopy, Light, and Electrons ❮ 145❯ Answers and Explanations
- D—This configuration represents a noble gas
(neon). The outer s and p orbitals are filled. - C—Transition elements have partially filled d
orbitals. This configuration is for the metal zir-
conium, Zr. - B—The single electron in the s orbital indicates
that this is the very reactive alkali metal lithium. - A—The 1s orbital is not filled. One indication of
excited states is one or more inner orbitals being
unfilled. - B—The electron configuration for iron is
1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 4s^2. To produce an iron(II)
ion, the two 4s electrons are removed first. - B—The elements that are normally diamagnetic
are those in the same columns of the periodic
table as Be, Zn, and He because all of the elec-
trons are paired. Atoms in all other columns are
normally paramagnetic. - D—Halogens have a valence shell with s^2 p^5.
- B—Transition metals have partially filled
d orbitals (d^1 -^10 ), along with an s^1 or s^2. - A—A 2s^3 configuration is not possible as s-orbitals
cannot accommodate more than two electrons. - C—The outer s electrons are not present in
most transition metal ions; however, d electrons
may be present. C could be V^2 +, Cr^3 +, or Mn^4 +
(among other choices).
11. C—Atoms with only completely filled shells or
subshells are diamagnetic; all others are paramag-
netic. From the choices given, the elements with
complete shells or subshells are Be, Mg, Xe, Kr,
Zn, and Ba. Only one answer consists of atoms
from this group. It might be helpful to consult
the periodic table, as these elements are in groups
2, 12, and 18.
12. C—The four electrons in the oxygen 2p orbitals
are arranged with one pair and two unpaired elec-
trons with spins parallel. This makes the oxygen
atom paramagnetic. This arrangement is due to
Hund’s rule.
13. A—The Pauli exclusion principle restricts the
number of electrons that can occupy a single
orbital.
14. B—The d orbitals are shielded more efficiently
than the s orbitals. Thus, the less shielded d
orbitals do not fill as readily as s orbitals with
similar energy.
15. A—Calcium will form a +2 ion (Ca^2 +), and X
will need to gain two electrons to fill its outer
shell and become a –2 ion (X^2 - ). The simplest
formula for a compound containing a +2 ion
and a –2 ion would be CaX. The other answers
involve different charges or a formula that has
not been simplified.
16. C—Diffraction is a wave phenomenon; there-
fore, the observation of diffraction proves the
wave properties of electrons (matter).