Unit Quiz
Quiz Instructions
This quiz assesses your understanding of all atomic theory concepts covered in this unit. Complete all 10 questions without looking at your notes first, then check your answers.
Topics Covered
- Electron configuration and orbital filling
- Periodic trends (atomic radius, ionization energy, electronegativity)
- Valence electrons and group relationships
- Data interpretation and trend analysis
Scoring Guide
- 9-10 correct: Excellent - Ready to move on!
- 7-8 correct: Good - Review missed concepts
- 5-6 correct: Fair - Additional practice recommended
- Below 5: Review the unit lessons before retaking
Quiz Questions
Question 1: Write the electron configuration for chlorine (Cl, atomic number 17).
Answer: 1s2 2s2 2p6 3s2 3p5
Check: 2 + 2 + 6 + 2 + 5 = 17 electrons
Question 2: How many valence electrons does phosphorus (P) have?
Answer: 5 valence electrons
P is in Group 15. Its outer shell configuration is 3s2 3p3 = 5 valence electrons.
Question 3: Which has a larger atomic radius: potassium (K) or calcium (Ca)?
Answer: Potassium (K) has a larger atomic radius.
Both are in period 4. Ca is to the right of K, so it has more protons pulling on the same number of shells, making it smaller.
Question 4: Arrange in order of increasing ionization energy: Na, Mg, Al
Answer: Na < Al < Mg
Generally increases across a period, but Al has a slight dip due to its 3p1 electron being easier to remove than Mg's 3s2. The general trend is Na < Mg and Na < Al.
Question 5: Write the noble gas shorthand electron configuration for iron (Fe, atomic number 26).
Answer: [Ar] 4s2 3d6
Argon accounts for the first 18 electrons.
Question 6: Which element has the highest electronegativity: Li, C, or F?
Answer: Fluorine (F)
All three are in period 2. Electronegativity increases across a period, and F is farthest to the right.
Question 7: What is the electron configuration of Cr (chromium, atomic number 24)?
Answer: [Ar] 4s1 3d5
Chromium is an exception. A half-filled d subshell is more stable than [Ar] 4s2 3d4.
Question 8: Compare the atomic radius of F and Cl. Which is larger and why?
Answer: Chlorine (Cl) is larger.
Both are in Group 17, but Cl is in period 3 while F is in period 2. Atomic radius increases down a group because electrons occupy higher energy levels farther from the nucleus.
Question 9: An element has the electron configuration [Ne] 3s2 3p4. Identify the element and predict its most likely ion.
Answer: The element is sulfur (S). It will most likely form S2- (sulfide ion).
Sulfur needs 2 more electrons to complete its octet and achieve noble gas configuration [Ar].
Question 10: Explain why first ionization energy generally increases across a period but there are exceptions at certain elements.
Answer: First ionization energy increases across a period because nuclear charge increases while electrons are added to the same energy level. The electrons are held more tightly.
Exceptions occur at: (1) Group 13 elements (like B, Al) where the electron is in a new p orbital that's higher in energy and easier to remove; (2) Group 16 elements (like O, S) where electron pairing in p orbitals creates repulsion, making one electron easier to remove.
Self-Assessment
After completing the quiz, count your correct answers and use the scoring guide above to evaluate your mastery.
Review Recommendations
- Missed questions 1, 5, 7: Review electron configuration and exceptions
- Missed questions 2, 9: Review valence electrons and ion formation
- Missed questions 3, 8: Review atomic radius trends
- Missed questions 4, 6, 10: Review ionization energy and electronegativity trends
Next Steps
- Scored 9-10: Congratulations! You have mastered atomic theory. Move on to Chemical Bonding.
- Scored 7-8: Review the specific topics where you made errors, then retake the quiz.
- Scored 5-6: Work through Guided Practice and Common Mistakes again before retaking.
- Scored below 5: Start from Electron Configuration and work through the entire unit again.
Additional Resources
- Return to any lesson for review
- Create flashcards for electron configurations
- Practice with ACT Science passages on atomic properties