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CHAPTER 4 Problems
1) Classify each of the following elements as a metal, a nonmetal, or a metalloid. Also
identify the element as an alkali metal, alkaline earth metal, halogen, noble gas, or
transition metal, as appropriate.
a) As, b) Cl, c) Xe, d) Ba, e) Fe, f) P, g) Li, h) I, i) B, j) Si
2) What are valence electrons?
3) For main group elements the number of valence electrons and the approximate value
for Zeff (effective charge of the nucleus observed by the valence electrons) are equal to its
group number. Show that this is true for the following elements by writing the electron
configuration for the element, finding the number of valence electrons, finding the
approximate value for Zeff, and comparing the result to the group number for the atom.
Recall that the approximate value for Zeff is given by the relationship
Zeff  # protons - # core electrons = atomic number - number of core electrons
a) Al, b) Sr, c) K, d) Br, e) P, f) S, g) C
4) (Burdge, 4.16) Group the following electron configurations in pairs that would
represent elements with similar chemical properties:
a) 1s2 2s2 2p6 3s2
b) 1s2 2s2 2p3
c) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
d) 1s2 2s2
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e) 1s 2s 2p
f) 1s2 2s2 2p6 3s2 3p3
5) Identify how the atomic radius changes in going from left to right in the periodic table,
and explain why this behavior is seen.
6) Identify how the atomic radius changes in going from top to bottom in the periodic
table, and explain why this behavior is seen.
7) a) Define ionization energy. b) Explain why ionization energy measurements are
usually made when atoms are in the gas state. c) Why is the second ionization energy
always greater than the first ionization energy for any element?
8) (Burdge, 4.34) a) Define electron affinity. b) Explain why electron affinity measurements are made with gaseous atoms. c) Ionization energy is always a positive quantity,
whereas electron affinity may be either positive or negative. Explain.
9) On the basis of their position in the periodic table, select the atom with the larger
atomic radius in each of the following pairs:
a) Na, Si
b) Ba, Be
c) N, F
d) Br, Cl
e) Ne, Kr
10) (Burdge, 4.50) Arrange the following in order of increasing first ionization energy:
Na, Cl, Al, S, Cs.
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11) Which element in each of the following sets is expected to have the largest value for
first ionization energy? Why?
a) Mg, Na, Sr
b) As, Cl, P
12) (Burdge, 4.54) The first and second ionization energies for K are 419. kJ/mol and
3052. kJ/mol, and for Ca are 590. kJ/mol and 1145. kJ/mol. Compare their values and
comment on the differences.
13) The following ionization energies are observed for an atom of a particular main group
element:
IE1 = 787. kJ/mol
IE2 = 1577. kJ/mol
IE3 = 3231. kJ/mol
IE4 = 4356. kJ/mol
IE5 = 16091. kJ/mol
IE6 = 19784. kJ/mol
IE7 = 23783. kJ/mol
Which group is the element most likely a member of? Why?
14) (Burdge, 4.61) Explain why alkali metals have a greater affinity for electrons than
alkaline earth metals.
15) Compare the physical and chemical properties of metals and nonmetals.
16) (Burdge, 4.68) Write the ground state electron configurations of the following ions:
a) Li+ b) H- c) N3- d) F- e) S2- f) Al3+ g) Se2- h) Br17) (Burdge, 4.72) Write the ground state electron configurations of the following
transition metal ions: a) Sc3+, b) Ti4+, c) V5+, d) Cr3+, e) Mn2+
18) (Burdge, 4.89) Indicate which one of the two species in each of the following pairs is
smaller: a) Cl or Cl- b) Na or Na+ c) O2- or S2- d) Mg2+ or Al3+ e) Au+ or Au3+
19) For each of the following main group elements give the ion most likely to form:
a) Mg, b) F, c) Se, d) Rb, e) O, f) Ba
20) As a group the noble gases are very stable chemically. Why?
21) State whether each of the properties of the main group elements generally increases
or decreases from left to right across the period, and from top to bottom within a group
a) metallic character, b) atomic size, c) first ionization energy
22) (Burdge, 4.98) Write equations representing the following processes:
a) The electron affinity of Sb) The third ionization energy for titanium
c) The electron affinity of Mg2+
d) The ionization energy for O2-
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