Trends in atomic and ionic radii, ionization potential and electron affinity - Question Bank

1. The energy required to remove the first electron from a neutral atom is the first ionization energy. The energy required to remove the second electron from the resulting unipositive ion is the second ionization energy. Which relationship is ALWAYS true?
A) IE1(X) > IE2(X)
B) IE1(X) < IE2(X)
C) IE1(X) = IE2(X)
D) IE1(X) < IE2(X+)
2. Which of the following isoelectronic species will have the smallest ionic radius?
A) Ar
B) K+
C) Ca2+
D) S2-
3. Which statement best explains the anomalous electron affinity of some elements like Phosphorus (P) compared to Sulfur (S)?
A) Phosphorus has a smaller atomic radius.
B) Sulfur has a more stable half-filled p-orbital configuration.
C) The added electron in Phosphorus enters a half-filled p-orbital, experiencing less repulsion than in Sulfur's doubly occupied p-orbital.
D) Sulfur has a higher ionization potential.
4. The trend in atomic radii down Group 17 (Halogens) is:
A) F > Cl > Br > I
B) I > Br > Cl > F
C) F < Cl < Br < I
D) Cl > F > Br > I
5. Which of the following is the correct order of decreasing atomic radii for Li, Be, B, C?
A) Li > Be > B > C
B) C > B > Be > Li
C) Li > C > B > Be
D) Be > B > C > Li
6. Which of the following is the correct order of increasing electron affinity for Li, Be, B, C?
A) Li < Be < B < C
B) C < B < Be < Li
C) Li < C < B < Be
D) Be < B < C < Li
7. Which of the following is the correct order of decreasing first ionization potential for Li, Be, B, C?
A) Li > Be > B > C
B) C > B > Be > Li
C) Li > C > B > Be
D) Be > B > C > Li
8. Why does Sodium (Na) have a very high second ionization energy?
A) The second electron is removed from a noble gas configuration.
B) The second electron is removed from the same valence shell as the first.
C) The effective nuclear charge decreases significantly after removing the first electron.
D) The atomic radius increases after removing the first electron.
9. Which element is expected to have the highest second ionization energy?
A) Sodium (Na)
B) Magnesium (Mg)
C) Aluminum (Al)
D) Silicon (Si)
10. Which of the following trends is INCORRECT?
A) Atomic radius increases down a group.
B) Ionization potential decreases across a period.
C) Electron affinity becomes more negative across a period (generally).
D) Ionic radius of cations decreases with increasing positive charge.
11. In the series O2-, F-, Na+, Mg2+, which species has the smallest radius?
A) O2-
B) F-
C) Na+
D) Mg2+
12. In the series O2-, F-, Na+, Mg2+, which species has the largest radius?
A) O2-
B) F-
C) Na+
D) Mg2+
13. Consider isoelectronic species (same number of electrons). For example, O2-, F-, Na+, Mg2+. Which statement is true about their radii?
A) The radius increases with increasing nuclear charge.
B) The radius decreases with increasing nuclear charge.
C) The radius is the same for all.
D) The radius depends on the number of neutrons.
14. Which of the following pairs of elements would have the largest difference in atomic radii?
A) Li and Be
B) Na and K
C) Cl and Br
D) O and F
15. Why does Fluorine have a lower electron affinity than Chlorine?
A) Fluorine has a larger atomic radius.
B) Chlorine has a higher effective nuclear charge.
C) The small size of the Fluorine atom leads to significant electron-electron repulsion when an electron is added.
D) Chlorine has a more stable electron configuration.
16. Why do noble gases have positive electron affinities?
A) They have a very high nuclear charge.
B) They have a stable, filled valence electron shell, and adding an electron requires forcing it into a higher energy level or causing repulsion.
C) Their atomic radii are very large.
D) They have very low ionization potentials.
17. Which of the following elements has a positive electron affinity (meaning energy is required to add an electron)?
A) Chlorine (Cl)
B) Bromine (Br)
C) Iodine (I)
D) Noble Gases (e.g., Ne)
18. Which of the following has the highest (most negative) electron affinity?
A) Na
B) Mg
C) Al
D) Si
19. Electron affinity generally increases across a period. Why?
A) Increase in atomic radius
B) Decrease in effective nuclear charge
C) Increase in effective nuclear charge and decrease in atomic radius, leading to stronger attraction for an incoming electron
D) Decrease in the number of valence electrons
20. Which element in the second period has the highest (most negative) electron affinity?
A) Lithium (Li)
B) Neon (Ne)
C) Fluorine (F)
D) Carbon (C)
21. Why does electron affinity generally decrease down a group?
A) Increase in nuclear charge
B) Increase in atomic radius and shielding, reducing the attraction for the incoming electron
C) Decrease in the number of valence electrons
D) Increase in ionization potential
22. As one moves down a group, electron affinity generally:
A) Increases
B) Decreases
C) Remains constant
D) Fluctuates significantly
23. For most elements, the addition of an electron results in energy release, meaning electron affinity is typically:
A) Positive
B) Negative
C) Zero
D) Either positive or negative
24. What is electron affinity?
A) The energy required to remove an electron from a neutral atom.
B) The energy change that occurs when an electron is added to a neutral gaseous atom to form a negative ion.
C) The energy released when an atom forms a positive ion.
D) The energy associated with the formation of a covalent bond.
25. Why does Oxygen have a lower first ionization energy than Nitrogen?
A) Oxygen has a smaller atomic radius.
B) Oxygen has a higher effective nuclear charge.
C) The electron removed from Oxygen is from a doubly occupied p-orbital, leading to repulsion.
D) Nitrogen has a more stable half-filled p-orbital configuration.
26. Which of the following elements has an unusually low first ionization potential compared to its neighbors in the same period?
A) Nitrogen (N)
B) Oxygen (O)
C) Fluorine (F)
D) Neon (Ne)
27. The second ionization potential of an element is always higher than its first ionization potential. Why?
A) The second electron is removed from a more stable configuration.
B) The second electron is removed from a positively charged ion, requiring more energy.
C) The nuclear charge increases after removing the first electron.
D) The shielding effect increases significantly after removing the first electron.
28. Which of the following has the highest first ionization potential?
A) Na
B) Mg
C) Al
D) Si
29. Why does ionization potential generally increase across a period?
A) Increase in atomic radius
B) Decrease in effective nuclear charge
C) Increase in effective nuclear charge and decrease in atomic radius
D) Decrease in the number of valence electrons
30. Which element in the second period has the highest first ionization potential?
A) Lithium (Li)
B) Neon (Ne)
C) Fluorine (F)
D) Carbon (C)
31. Which factor contributes most to the decrease in ionization potential down a group?
A) Increase in nuclear charge
B) Increase in the number of valence electrons
C) Increase in the distance of the valence electron from the nucleus and increased shielding
D) Decrease in atomic radius
32. As one moves down a group in the periodic table, what generally happens to the ionization potential?
A) It increases
B) It decreases
C) It remains constant
D) It fluctuates unpredictably
33. What is ionization potential (or ionization energy)?
A) The energy released when an electron is added to a neutral atom.
B) The energy required to remove the most loosely held electron from an isolated gaseous atom.
C) The energy released when an atom forms a covalent bond.
D) The energy required to form a metallic bond.
34. Which of the following ions has the smallest radius?
A) S2-
B) Cl-
C) K+
D) Ca2+
35. Which of the following ions has the largest radius?
A) Mg2+
B) Na+
C) Al3+
D) F-
36. Why does a cation have a smaller ionic radius than its parent atom?
A) Increased number of electrons
B) Decreased effective nuclear charge per electron and reduced electron-electron repulsion
C) Increased shielding effect
D) Addition of neutrons
37. Why does an anion have a larger ionic radius than its parent atom?
A) Increased nuclear charge
B) Decreased electron-electron repulsion
C) Increased electron-electron repulsion and decreased effective nuclear charge per electron
D) Addition of protons
38. Which ion is smaller: Cl- or F-?
A) Cl-
B) F-
C) They are the same size
D) Cannot be determined
39. When an atom gains an electron to form an anion, its ionic radius is generally:
A) Larger than its atomic radius
B) Smaller than its atomic radius
C) Equal to its atomic radius
D) Larger or smaller depending on the element
40. Which ion is larger: Na+ or K+?
A) Na+
B) K+
C) They are the same size
D) Cannot be determined
41. When an atom loses an electron to form a cation, its ionic radius is generally:
A) Larger than its atomic radius
B) Smaller than its atomic radius
C) Equal to its atomic radius
D) Unpredictable
42. Which of the following is expected to have the largest atomic radius?
A) Potassium (K)
B) Calcium (Ca)
C) Gallium (Ga)
D) Germanium (Ge)
43. Why is the atomic radius of Sodium (Na) larger than that of Magnesium (Mg)?
A) Sodium has more protons.
B) Magnesium has a higher effective nuclear charge acting on its valence electrons.
C) Sodium has more electron shells.
D) Magnesium has a greater shielding effect.
44. What is the primary reason for the decrease in atomic radius across a period?
A) Increase in the number of electron shells
B) Decrease in nuclear charge
C) Increase in effective nuclear charge with electrons added to the same shell
D) Decrease in the shielding effect of inner electrons
45. Which of the following is the correct order of increasing atomic radii for Li, Be, B, C?
A) Li < Be < B < C
B) C < B < Be < Li
C) Li < C < B < Be
D) Be < B < C < Li
46. The effective nuclear charge experienced by an outer electron generally increases as one moves across a period from left to right. What effect does this have on atomic radius?
A) It causes the atomic radius to increase.
B) It causes the atomic radius to decrease.
C) It has no significant effect on atomic radius.
D) It causes atomic radius to fluctuate.
47. Which element in the second period has the smallest atomic radius?
A) Lithium (Li)
B) Neon (Ne)
C) Fluorine (F)
D) Carbon (C)
48. As one moves down a group in the periodic table, what generally happens to the atomic radius?
A) It increases
B) It decreases
C) It remains constant
D) It fluctuates unpredictably
49. Which of the following factors primarily determines the atomic radius of an element?
A) Number of neutrons
B) Number of protons
C) Number of electron shells and effective nuclear charge
D) Isotopic abundance
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