Unit 2 Practice Questions
Chapter 6
1. One of the outermost electrons in a potassium atom can be described by which of the following quantum
numbers?
(A) 4, 0, 0, ½
(B) 4, 0, 1, ½
(C) 4, 1, 0, ½
(D) 4, 1, 1, ½
(E) 4, 1, -1, ½
2. Which of the following quantum numbers can describe a 3p electron? ( for p, l = 1)
(A) 3, 0, 1, ½
(B) 3, 2, 1, ½
(C) 3, 1, 2, ½
(D) 3, 0, -1, ½
(E) 3, 1, -1, ½
3. Which set of quantum numbers can describe a valence electron in selenium? (4p electron)
(A) 4, 2, 2, ½
(B) 4, 1, 0, ½
(C) 4, 1, 2, ½
(D) 4, 2, 1, ½
(E) 4, 0, 1, ½
4. In a specific atom, how many electrons can have the quantum numbers n = 5, l = 3? (when l = 3, this is an f
orbital…14 electrons max)
(A) 2
(B) 10
(C) 14
(D) 7
(E) 5
5. Which of the following represent impossible combinations of n and l?
(A) 1p
(B) 4s
(C) 5f
(D) 2d
(E) 3p
1s
2s
3s
4s
5s
2p
3p 3d
4p 4d 4f
5p 5d 5f etc…
Base your answers to questions 8 through 10 on the electron configuration for the ground state of element X,
given below.
1s22s22p63s23p4
8. How many valence electrons does element X have? 6 (valence e-s are the ones in the highest n level)
9. Which element is X most chemically similar to? (has same # of valence e-s as O…is in same group as O)
(A) Be
(B) C
(C) N
(D) O
(E) Ne
10. What is a possible excited state of element X? (X = sulfur; one 3s electron jumped to the 3p subshell)
(A) 1s22s22p63s23p5 (B) 1s22s22p63s13p5
(C) 1s22s22p63s23p4 (D) 1s22s22p63s23p44s2 (E) [Ne]3s23p4
Ca, V, Co, Zn, As
Ca: [Ar]
(all electrons are paired, NOT paramagnetic)
V: [Ar] 4s2 3d3 (the 3 d electrons are unpaired, PARAMAGNETIC)
Co: [Ar] 4s2 3d7 (3 of the d electrons are unpaired, PARAMAGNETIC)
Zn: [Ar] 4s2 3d10 (all electrons are paired, NOT paramagnetic)
As: [Ar] 4s2 3d10 4p3 (the 3 p electrons are unpaired, PARAMAGNETIC)
11. Gaseous atoms of which of the elements above are paramagnetic? (have unpaired electrons)
4s2
(A) Ca and As only
(B) Zn and As only
(C) Ca, V, and Co only
(D) V, Co, and As only
(E) V, Co, and Zn only
Use these answers for questions 12 - 15.
(A) 1s2 2s22p5 3s23p5 (excited-state sulfur)
(B) 1s2 2s22p6 3s23p6 (8 valence e-s)
(C) 1s2 2s22p62d10 3s23p6 (impossible to have 2d)
12.
13.
14.
15.
(D) 1s2 2s22p6 3s23p63d5 (not valid – 4s before 3d)
(E) 1s2 2s22p6 3s23p63d3 4s2 (Vanadium, Z = 23)
An impossible electronic configuration. C
The ground-state configuration for the atoms of a transition element. E
The ground-state configuration of a negative ion of a halogen. (8 valence electrons) B
The ground-state configuration of a common ion of an alkaline earth element. B
(Group 2A metal – loses two e-s to form 2+ ion and achieve noble gas config… 8 valence electrons)
Questions 16-19
(A) Heisenberg uncertainty principle (can’t know BOTH where and how fast e-s are moving)
(B) Pauli exclusion principle (no two electrons can have the same 4 quantum numbers in a given atom)
(C) Hund's rule (must put one electron in each orbital in a given shell before pairing them to minimize
e-e repulsion)
(D) Shielding effect
(E) Wave nature of matter
16. Can be used to predict that a gaseous carbon atom in its ground state is paramagnetic. C
17. Explains the experimental phenomenon of electron diffraction. E (matter can be diffracted (bent when
passed through an opening) just like energy waves can)
18. Indicates that an atomic orbital can hold no more than two electrons. B
19. Predicts that it is impossible to determine simultaneously the exact position and the exact velocity of an
electron. A
Chapter 7
20. Which will experience the greater effective nuclear charge, the electrons in the n = 3 shell of Ar or the n =
3 shell of Kr? Which will be closer to the nucleus? Justify you answer. N = 3 electrons in Kr
experience a greater Z* (more protons in Kr) and thus have a greater probability of being closer to the nucleus.
21. Why does F have a larger first ionization energy than O? F has a greater Z* and the outer electrons in both
elements are approx. the same distance from the nucleus.
22. Why is the second ionization energy of an atom always greater than its first ionization energy? more energy
is required to overcome the larger Zeff of the 1+ cation than that of the neutral atom
23. For each of the following sets of atoms and ions, arrange the members in order of increasing size:
(i) Se2–, Te2–, Se
(ii) Ca, Ti4+, Sc3+
(iii) Fe2+, Co3+, Fe3+
(iv) Mg2+, Ne, Na+
224+
3+
3+
3+
2+
Se < Se < Te
Ti < Sc < Ca
Co < Fe < Fe
Mg2+ < Na+ < Ne
24.
What is an isoelectronic series? A group of atom or ions that have the same number of electrons
Which of the above are examples of an isoelectronic series? iv only
25. Which neutral atom is isoelectronic with each of the following ions?
(i) Cl– Ar
(ii) Se2– Kr
(iii) Mg2+ Ne
26. Write equations that show the processes that describe the first, second, and third ionization energies of a
tellurium atom.
First IE: Te(g)  Te+(g) + e-
Second IE: Te+(g)  Te2+(g) + e-
Third IE: Te2+(g)  Te3+(g) + e-
Ionization Energies (kJ/mol)
First Second Third Fourth Fifth Sixth
786
1577 3232 4355 16091 19784
27. Based on the ionization energies listed above, the element is most likely
(A) Sb
(B) Ca
(C) Si
(D) Ga
(E) Se
(HUGE jump from fourth to fifth IE  has 4 valence electrons (silicon)
28. An element has 1st, 2nd, and 3rd ionization energies given in kJ mol-1.
IE1
IE2
IE3
735 1,450 7,720
This element is a member of which group?
(A) Alkali metals
(D) Noble gases
(B) Transition elements
(E) Alkaline earth metals
(C) Halogens
(HUGE jump from IE2 to IE3  Group 2A (Alkaline earth metal)
28. Which atom has the lowest second ionization energy?
(A) Be
(B) Na
(C) K
(D) Ar
(E) Mg
(Group 2A – wants to get rid of 2 valence e-s. IE2 for Mg is lower than for Be because Mg has another
principal energy level – more shielding by core electrons, and thus a lower Zeff)
29. If you start at Fr and end at Li in Group 1A of the periodic table, what general trend is observed?
(A) Increasing metallic characteristics
(B) Decreasing electronegativities
(C) Decreasing ionization energies
(D) Decreasing atomic radii
(E) Increasing number of oxidation states
Base your answers to the following questions on the following types of energy:
(A) Ionization energy
(B) Electromagnetic energy
(C) Electron affinity
30. Energy that travels in waves and is defined by wavelength and frequency. ____B
31. Energy required to remove an electron from an atom or ion in the gaseous state. ____ A
32. Energy released when an electron is added to an atom in the gaseous state. ____ C