Mastering Periodic Trends – Ionization Energy, Electronegativity & Atomic Radius

How well do you really know the periodic table? On the DAT, general chemistry questions often dive into the trends—not just the facts. From ionization energy to atomic radius, the DAT loves to test whether you can analyze and compare trends across the table.

In this blog, we’ll simplify periodic trends into a visual memory system, give you DAT-style questions to practice, and help you lock in the high-yield rules.

📊 Why Periodic Trends Matter on the DAT

Expect 2–4 periodic trend questions in the General Chemistry section. Most questions ask you to:

• Compare elements across a period or down a group

• Predict reactivity or stability

• Interpret data tables or apply logic to trends

🧠 These questions are fast if you know the rules—and a time trap if you don’t.

🔬 Key Periodic Trends You Must Know

1. Atomic Radius

• Increases ↓ a group

• Decreases → across a period

🧠 Why? More protons = stronger nuclear pull = smaller atoms.

2. Ionization Energy (IE)

• Decreases ↓ a group

• Increases → across a period

🧠 IE = Energy needed to remove an electron. Smaller atoms = tighter hold on electrons.

3. Electronegativity

• Follows same trend as IE

• Highest in Fluorine (F)

🧠 Measures an atom’s desire to attract electrons.

4. Electron Affinity

• Increases → across a period

• Generally decreases ↓ a group
  (Note: Group 18 = exception; noble gases don't want more electrons.)

📚 DAT-Style Practice Question

Q: Which of the following has the highest ionization energy?
A. Li
B. Be
C. B
D. Ne

✅ Answer: D. Ne — It's a noble gas, stable, and very small = very high ionization energy.

🎯 How to Master Periodic Trends for the DAT

✅ Use visuals to memorize directional arrows
✅ Practice “which is greater” comparison questions
✅ Use the KOTC Adaptive Q-Bank to target trend-based logic
✅ Review group anomalies, like why Group 2 is harder to ionize than Group 1
✅ Drill questions that integrate trends with chemical reactivity

📲 Check out kingofthecurve.org/studyscience for concept-specific breakdowns and visuals like these.

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