Complete Theory

Worked Examples

Example 1Electron configuration of iron

Example 2Hydrogen spectral line (Balmer)

Exercise 1Electron configurationMedium

📋 Problem to solve

Write the complete electron configuration of chlorine (

Z=17

) and potassium (

Z=19

), and state the valence electrons for each.

📌 Given data

Chlorine Z = 17Potassium Z = 19

Exercise 2Periodic propertiesMedium

📋 Problem to solve

Order by increasing atomic radius: Na, Cl, K. Explain.

📌 Given data

Na (Z=11)Cl (Z=17)K (Z=19)

Exercise 3Ionization energyHard

📋 Problem to solve

Why is the first ionization energy of magnesium greater than that of aluminum, even though aluminum has a higher

Z

📌 Given data

Mg (Z=12):

1s^2\,2s^2\,2p^6\,3s^2

Al (Z=13):

1s^2\,2s^2\,2p^6\,3s^2\,3p^1

📚

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