CHM009 · Atoms, Elements & Periodic Table · Classes 8–12
Periodic Table 3D Trends
Objective: To see trends in atomic radius, ionisation energy and electronegativity across the periodic table.
🧰 Virtual materials and apparatus
- Virtual 3D periodic table (Z 1–36)
- Bars whose height shows the chosen property
📐 Formulas and SI units
radius ↓ across, ↑ down
IE and EN ↑ across, ↓ down
💡 Theory
Across a period the nuclear charge rises while electrons go into the same shell, so atoms get smaller and hold electrons more tightly: ionisation energy and electronegativity increase. Down a group extra shells make atoms larger and outer electrons easier to remove.
🪜 Guided virtual procedure
- Choose a property.
- Look along a row (period) and down a column (group).
- Select fluorine and read its electronegativity.
- Switch to atomic radius and find the largest atom shown.
- Describe each trend in one sentence.
📋 Observations Simulated values
✅ Result and conclusion
Fluorine has the highest electronegativity, 3.98, at the top right of the table.
🔬 Real lab vs simulation
Values are reference data (Pauling electronegativity, covalent radii, first ionisation energies); there are exceptions to every trend, such as the dip from N to O in ionisation energy.
⚠️ Safety
Data exploration only. Real laboratory chemicals are handled only by teachers in a school laboratory.
❓ Quick check
1. The most electronegative element is…
2. Atomic radius down a group…
3. Noble gases have no Pauling electronegativity because…
🏋️ Practice
EasyWhich is larger: Na or Cl?
Answer: Na
MediumWhich has higher IE: Li or Ne?
Answer: Ne
ChallengeTrend of EN across period 3?
Answer: Increases from Na to Cl