Question

What are the electron configurations for the f-block elements?

Answer 1

There is not much of a pattern. You'll just have to look and see... For the lanthanides...

`"La": [Xe] 6s^2 5d^1`

`"Ce": [Xe] 6s^2 4f^1 5d^1`

`color(green)("Pr": [Xe] 6s^2 4f^3 5d^0)`

`color(green)("Nd": [Xe] 6s^2 4f^4 5d^0)`

`color(green)("Pm": [Xe] 6s^2 4f^5 5d^0)`

`color(green)("Sm": [Xe] 6s^2 4f^6 5d^0)`

`color(green)("Eu": [Xe] 6s^2 4f^7 5d^0)`

`"Gd": [Xe] 6s^2 4f^7 5d^1`

`color(green)("Tb": [Xe] 6s^2 4f^9 5d^0)`

`color(green)("Dy": [Xe] 6s^2 4f^10 5d^0)`

`color(green)("Ho": [Xe] 6s^2 4f^11 5d^0)`

`color(green)("Er": [Xe] 6s^2 4f^12 5d^0)`

`color(green)("Tm": [Xe] 6s^2 4f^13 5d^0)`

`color(green)("Yb": [Xe] 6s^2 4f^14 5d^0)`

`color(green)("Lu": [Xe] 6s^2 4f^14 5d^1)`

The green ones are ones that follow the Aufbau Principle. And for the actinides:

`"Ac": [Rn] 7s^2 6d^1`

`"Th": [Rn] 7s^2 6d^2`

`"Pa": [Rn] 7s^2 5f^2 6d^1`

`"U": [Rn] 7s^2 5f^3 6d^1`

`"Np": [Rn] 7s^2 5f^4 6d^1`

`color(green)("Pu": [Rn] 7s^2 5f^6 6d^0)`

`color(green)("Am": [Rn] 7s^2 5f^7 6d^0)`

`"Cm": [Rn] 7s^2 5f^7 6d^1`

`color(green)("Bk": [Rn] 7s^2 5f^9 6d^0)`

`color(green)("Cf": [Rn] 7s^2 5f^10 6d^0)`

`color(green)("Es": [Rn] 7s^2 5f^11 6d^0)`

`color(green)("Fm": [Rn] 7s^2 5f^12 6d^0)`

`color(green)("Md": [Rn] 7s^2 5f^13 6d^0)`

`color(green)("No": [Rn] 7s^2 5f^14 6d^0)`

`color(green)("Lr": [Rn] 7s^2 5f^14 6d^1)`

Again, the green ones are the normal ones. You obviously don't have to memorize these.