Effective Nuclear Charge Simulation

Guided explanationLive observation

The valence electron feels the nuclear pull remaining after shielding.

Nuclear charge Z11

Shielding S8.80

Effective charge2.20

Attractive force14.67 nN

Effective Nuclear Charge LabPaused

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Start with the idea

An electron rarely feels the nucleus’s full charge. Other electrons partly screen the attraction.

Protons create nuclear charge Z.
Other electrons contribute shielding S.
The remaining pull is effective nuclear charge.

Electrostatic analyzer

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Element

Model shielding S8.80

Electron distance186 pm

Simulation speed1×

Calculated result

Protons Z11

Shielding S8.80

Z effective2.20

Force0.16 nN

View and focus

Period trend graph

Teacher demonstrations

Guided visual lecture

Chapter 1 of 80%

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1. What effective nuclear charge means

Watch: Full nuclear pull and screened pull separate.

Chapters

Equations and model

Z_eff = Z − S

F = k · Z_eff · e² ÷ r²

Z is proton number, S is the shielding estimate, r is electron distance, and k is Coulomb’s constant.

Learning objectives

Calculate effective nuclear charge from Z and S.
Explain shielding and penetration.
Predict trends across periods and down groups.
Separate charge effects from distance effects.

Suggested investigations

Keep distance fixed and move from lithium to fluorine.
Double distance and compare force.
Hold Z fixed while increasing S.
Compare 2s and 2p penetration in Teacher mode.

Questions for exploration

Why does shielding not cancel every added proton across a period?
How can similar effective charge produce different atomic sizes?
Why is this model an estimate?

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