,CHEM 104 Module 6 Exam General Chemistry II
w/Lab | Portage | 26/27|Q&A Actual (PDF)
1. Which periodic trend correctly describes the change in atomic radius as you move from left to right
across a period?
A) Atomic radius increases because nuclear charge decreases.
B) Atomic radius decreases because effective nuclear charge increases.
C) Atomic radius remains constant because the number of shells does not change.
D) Atomic radius increases because electron shielding increases.
Correct Answer: Atomic radius decreases because effective nuclear charge increases.
Rationale: Across a period, protons are added to the nucleus while electrons enter the same shell. The
increasing effective nuclear charge pulls electrons closer, decreasing atomic radius. Option A reverses
the trend. Option C ignores the contraction caused by increased nuclear charge. Option D confuses
shielding effects, which are relatively constant across a period.
2. Which of the following elements is classified as a metalloid?
A) Aluminum
B) Silicon
C) Sulfur
D) Potassium
,Correct Answer: Silicon
Rationale: Silicon is a metalloid, possessing properties intermediate between metals and nonmetals,
and is a semiconductor. Aluminum is a post-transition metal, sulfur is a nonmetal, and potassium is an
alkali metal. Options A, C, and D do not fall along the metalloid staircase.
3. What is the correct electron configuration for the chloride ion, Cl⁻?
A) 1s² 2s² 2p⁶ 3s² 3p⁶
B) 1s² 2s² 2p⁶ 3s² 3p⁵
C) 1s² 2s² 2p⁶ 3s² 3p⁴
D) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Correct Answer: 1s² 2s² 2p⁶ 3s² 3p⁶
Rationale: Chlorine (Z=17) has the configuration [Ne] 3s² 3p⁵. Gaining one electron to form Cl⁻ fills the
3p subshell, giving [Ne] 3s² 3p⁶, which is isoelectronic with argon. Option B is the neutral chlorine
atom. Options C and D are incorrect electron counts.
4. Which halogen has the highest electronegativity?
A) Fluorine
B) Chlorine
C) Bromine
, D) Iodine
Correct Answer: Fluorine
Rationale: Electronegativity decreases down Group 17 as atomic size increases and effective nuclear
charge on bonding electrons decreases. Fluorine is the most electronegative element on the periodic
table. Chlorine, bromine, and iodine are less electronegative than fluorine.
5. In the complex ion [Cu(NH₃)₄]²⁺, what is the coordination number of copper?
A) 2
B) 4
C) 6
D) 8
Correct Answer: 4
Rationale: The coordination number is the number of ligand donor atoms bonded to the central metal
ion. Four ammonia ligands are bonded to Cu²⁺, so the coordination number is 4. Options A, C, and D
do not match the number of ligands shown in the formula.
6. Which of the following statements about noble gases is correct?
A) They readily form ionic compounds with alkali metals.
B) They have completely filled valence electron shells and are generally unreactive.
w/Lab | Portage | 26/27|Q&A Actual (PDF)
1. Which periodic trend correctly describes the change in atomic radius as you move from left to right
across a period?
A) Atomic radius increases because nuclear charge decreases.
B) Atomic radius decreases because effective nuclear charge increases.
C) Atomic radius remains constant because the number of shells does not change.
D) Atomic radius increases because electron shielding increases.
Correct Answer: Atomic radius decreases because effective nuclear charge increases.
Rationale: Across a period, protons are added to the nucleus while electrons enter the same shell. The
increasing effective nuclear charge pulls electrons closer, decreasing atomic radius. Option A reverses
the trend. Option C ignores the contraction caused by increased nuclear charge. Option D confuses
shielding effects, which are relatively constant across a period.
2. Which of the following elements is classified as a metalloid?
A) Aluminum
B) Silicon
C) Sulfur
D) Potassium
,Correct Answer: Silicon
Rationale: Silicon is a metalloid, possessing properties intermediate between metals and nonmetals,
and is a semiconductor. Aluminum is a post-transition metal, sulfur is a nonmetal, and potassium is an
alkali metal. Options A, C, and D do not fall along the metalloid staircase.
3. What is the correct electron configuration for the chloride ion, Cl⁻?
A) 1s² 2s² 2p⁶ 3s² 3p⁶
B) 1s² 2s² 2p⁶ 3s² 3p⁵
C) 1s² 2s² 2p⁶ 3s² 3p⁴
D) 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Correct Answer: 1s² 2s² 2p⁶ 3s² 3p⁶
Rationale: Chlorine (Z=17) has the configuration [Ne] 3s² 3p⁵. Gaining one electron to form Cl⁻ fills the
3p subshell, giving [Ne] 3s² 3p⁶, which is isoelectronic with argon. Option B is the neutral chlorine
atom. Options C and D are incorrect electron counts.
4. Which halogen has the highest electronegativity?
A) Fluorine
B) Chlorine
C) Bromine
, D) Iodine
Correct Answer: Fluorine
Rationale: Electronegativity decreases down Group 17 as atomic size increases and effective nuclear
charge on bonding electrons decreases. Fluorine is the most electronegative element on the periodic
table. Chlorine, bromine, and iodine are less electronegative than fluorine.
5. In the complex ion [Cu(NH₃)₄]²⁺, what is the coordination number of copper?
A) 2
B) 4
C) 6
D) 8
Correct Answer: 4
Rationale: The coordination number is the number of ligand donor atoms bonded to the central metal
ion. Four ammonia ligands are bonded to Cu²⁺, so the coordination number is 4. Options A, C, and D
do not match the number of ligands shown in the formula.
6. Which of the following statements about noble gases is correct?
A) They readily form ionic compounds with alkali metals.
B) They have completely filled valence electron shells and are generally unreactive.
