Main transition elements (d-block)
Ten columns, eight group labels
1. The transition elements and their series
2. Eight labels, how many columns?
The d-block's group labels are IIIB, IVB, VB, VIB, VIIB, VIII, IB and IIB. That's eight labels.
Pick the right answer
Predict: how many vertical columns does the d-block have?
- A. 8: one column per label
- B. 10
- C. 5: one per d orbital
الشرح
The d-block has 10 vertical columns, because the d sublevel can hold up to 10 electrons. There are eight labels because group VIII covers three columns: (8), (9) and (10).
3. Ten columns for ten d electrons
In the main transition elements, electrons occupy the d sublevel in sequence. Since the d sublevel can take up to ten electrons, it contains ten vertical columns.
First column
↑
(n−1)dns²\ (n-1)d¹
Last column
↑↓↑↓↑↓↑↓↑↓
(n−1)dns²\ (n-1)d¹⁰
Here n is the period number. For example, in period 4, (n-1)d is 3d.
4. Walk across the d-block
Slide across the ten columns, from left to right. Watch the group label.
Column of the d-block 1
Group number 3
d electrons (general pattern) 1
(3) IIIB: the first column. Example: Sc.
Element table
group 3, group 4, group 5, group 6, group 7, group 8, group 9, group 10, group 11, group 12
- V: VB
- Co: VIII
- Cr: VIB
- Cu: IB
- Fe: VIII
- Mn: VIIB
- Ni: VIII
- Sc: IIIB
- Ti: IVB
- Zn: IIB
5. Group VIII: three columns
Group (8) VIII contains three vertical columns: (8), (9), (10). They differ from the other (B) groups: these elements are similar horizontally more than the elements below them in the same column.
Element table
group 8, group 9, group 10
- Co: VIII
- Fe: VIII
- Ni: VIII
So Fe, Co and Ni, side by side, are more alike than Fe and the elements below it.
6. Name the group
Pick the right answer
Palladium (Pd) is in column (10). Which group label does the book give this column?
- A. VIII
- B. XB
- C. IIB
- D. IB
الشرح
Column (10) belongs to group VIII, which covers columns (8), (9) and (10). So palladium is in group VIII.
Fill in the blanks
Technetium (Tc) is in period 5, group (7) VIIB. In the general pattern, its configuration ends with 5s²\ 4d^x, where x = _____.
الشرح
Group (3) has d¹, so group (7) has d⁵: Tc ends with 5s²\ 4d⁵.
Need a hint?
- Group (3) IIIB has d¹.
- In the pattern, each column to the right adds one d electron.
- Count from group (3) to group (7).
7. Neighbours or the one below?
Pick the right answer
According to the book, which pair is expected to be more similar?
- A. Ni and Pd (Pd is below Ni in the same column)
- B. Ni and Co (side by side in group VIII)
- C. Ni and Pt (Pt is two rows below Ni)
الشرح
Ni and Co are expected to be more similar. The book says group VIII elements are similar horizontally more than the elements below them in the same column.
True or false?
Group VIII is a single vertical column.
الشرح
Group VIII is not a single column: it covers three vertical columns, (8), (9) and (10), between VIIB (7) and IB (11).
8. Summary
- The d sublevel can take up to ten electrons, so the d-block has ten vertical columns.
- Groups from left to right: (3) IIIB, (4) IVB, (5) VB, (6) VIB, (7) VIIB, (8) (9) (10) VIII, (11) IB, (12) IIB.
- Group VIII = three columns, similar horizontally more than vertically.
- From one point of view, IIB is not considered as transition elements.
| Column | Group |
|---|---|
| (3) | IIIB |
| (4) | IVB |
| (5) | VB |
| (6) | VIB |
| (7) | VIIB |
| (8) | VIII |
| (9) | VIII |
| (10) | VIII |
| (11) | IB |
| (12) | IIB |
Can you explain how eight group labels cover ten columns?