Energy sublevels (s, p, d, f)
Why the d block has ten columns
1. Energy sublevels (s, p, d, f): from zero
2. Ten columns in the middle
The middle block of the periodic table has exactly 10 columns. Why 10, and not 8 or 18?
Element table
d-block
Pick the right answer
Predict: why 10 columns?
- A. Because only 10 such elements are known
- B. Because the sublevel filled there holds up to 10 electrons
- C. Because each period has 10 elements
Explanation
In the middle block, the d sublevel is being filled, and a d sublevel holds up to 10 electrons: one column for each electron.
3. Levels are divided into sublevels
Energy sublevels
The parts that a main energy level is divided into: s, p, d and f.
| Main level | n | Sublevels | Maximum electrons |
|---|---|---|---|
| K | 1 | 1s | 2 |
| L | 2 | 2s, 2p | 8 |
| M | 3 | 3s, 3p, 3d | 18 |
| N | 4 | 4s, 4p, 4d, 4f | 32 |
4. Open a level
Choose a main level. See which sublevels it has.
Main energy level (n) 3
M (n = 3): 3s, 3p, 3d → 2 + 6 + 10 = 18 electrons
Sublevels 3
Maximum electrons (2n²) 18
Add up the sublevels: you get the 2n² of the level.
5. Which sublevels exist?
Fill in the blanks
The N level (n = 4) has _____ sublevels. The one that can hold 14 electrons is _____.
Explanation
N has 4s, 4p, 4d and 4f. The 4f sublevel holds up to 14 electrons.
Pick the right answer
Which sublevel does NOT exist?
- A. 2d
- B. 4f
- C. 3d
- D. 2p
Explanation
2d does not exist: level 2 has two sublevels, 2s and 2p, and the d sublevel first appears at n = 3. 2p, 3d and 4f exist.
6. Summary
- Main level n has n sublevels: 1s; 2s 2p; 3s 3p 3d; 4s 4p 4d 4f.
- Maximum electrons: s 2, p 6, d 10, f 14.
- The d sublevel first appears at n = 3 (3d).
Can you explain why there is a 3d sublevel but no 2d?
Reveal
| Main level | n | Sublevels |
|---|---|---|
| L | 2 | 2s, 2p |
| M | 3 | 3s, 3p, 3d |
Level n has n sublevels. Level 2 has only 2s and 2p, so there is no 2d. The d sublevel first appears at n = 3 (3d).