CHAPTER 7 QUESTIONS
Try solving these questions before viewing the narrated answers online.
1.
A) If core electrons were perfect at screening valence electrons from the nuclear charge, what would
be the effective nuclear charge (Zeff) ‘experienced by’ the 4s valence electron of potassium (K)?
B) The actual value is 3.5. Explain the discrepancy between this value and your answer in part A.
2. Write the complete (full) ground state electron configuration for an arsenic (As) atom. Do not use condensed
electron configurations; that is, you must show every orbital that contains an electron.
3. Give a possible electron configuration for an excited state of the oxygen atom (O). Use the condensed form
involving a noble gas core.
4. Write out the full electron configuration (i.e. not the condensed electron configuration) for the cobaltous ion
Co2+.
5. Write down three ions that have the condensed electron configuration [Ne] in order of decreasing size (i.e.
largest first, smallest last). Explain your reasoning concerning the relative sizes.
6. Consider the series of ions Rb+, Br–, Se2–, Sr2+. Write the ions in order of decreasing size and offer an
explanation.
7. The 6th row of elements beginning with Cs has 32 members belonging to 4 different “blocks” of elements
beginning with two members of the s-block. What are the remaining three “blocks” and how many members
belong to each? Explain your answer in terms of electron configuration as one progresses along the row.
cont’d…
8. On the periodic table below:
A) Label with a capital A the column (group) that contains the element with the largest negative
electron affinity values.
B) Label with a capital B the column (group) that corresponds to the generalized electron
configuration: [noble gas]ns2(n-1)d10np1.
9. Three elements have the following electron configurations: 1s22s22p63s23p6, 1s22s22p63s2 and
1s22s22p63s23p64s1. The first ionization energies of these elements (not in the same order) are 419, 735,
and 1,527 kJ mol-1. The atom radii are 160, 98 and 235 pm. Identify the three elements and match them to
their ionization energies and radii using the table below.
Element
(symbol)
Ionization energy
(kJ mol-1)
Radius (pm)