# Main transition elements (d-block)

> Ten columns, eight group labels


## Objectives

- Explain why the d-block has ten vertical columns: the d sublevel can take up to ten electrons.
- Name the groups from left to right: (3) IIIB, (4) IVB, (5) VB, (6) VIB, (7) VIIB, (8) (9) (10) VIII, (11) IB, (12) IIB.
- Describe group VIII: three columns whose elements are similar horizontally more than the elements below them.

## 1. The transition elements and their series




## 2. Eight labels, how many columns?

Predict: how many vertical columns does the d-block have?

- 5: one per d orbital
- 10 ✓
- 8: one column per label

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).

[ar-EG] الـ d-block فيه 10 columns رأسية، عشان الـ d sublevel بيشيل لحد 10 electrons. والأسماء تمانية عشان الـ group VIII بيغطي تلات columns: (8) و(9) و(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 Last column Here n is the period number. For example, in period 4, $(n-1)d$ is 3d. This is the general pattern. A few elements, like Cr and Cu, differ slightly. They have their own lesson.


## 4. Walk across the d-block

Slide across the ten columns, from left to right. Watch the group label. Column of the d-block Group number d electrons (general pattern) **(3) IIIB**: the first column. Example: Sc. **(4) IVB**. Example: Ti. **(5) VB**. Example: V. **(6) VIB**. Example: Cr, one of the elements that differ slightly from the pattern. **(7) VIIB**. Example: Mn. **(8) VIII**: the first of its three columns. Example: Fe. **(9) VIII**: the second column of the same group. Example: Co. **(10) VIII**: the third column of the same group. Example: Ni. **(11) IB**. Example: Cu, the other element that differs slightly from the pattern. **(12) IIB**. Example: Zn. From one point of view, IIB is not considered as transition elements. The ten columns of the d-block; period 4 shows the group labels


## 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. Group VIII: columns (8), (9) and (10) So Fe, Co and Ni, side by side, are more alike than Fe and the elements below it. Group VIII is one column.


## 6. Name the group

Palladium (Pd) is in column (10). Which group label does the book give this column?

- IB
- IIB
- XB
- VIII ✓

Column (10) belongs to group VIII, which covers columns (8), (9) and (10). So palladium is in group VIII.

[ar-EG] الـ column (10) تبع الـ group VIII، اللي بيغطي الـ columns (8) و(9) و(10). يعني الـ palladium في الـ group VIII.
## 7. Neighbours or the one below?

According to the book, which pair is expected to be more similar?

- Ni and Pt (Pt is two rows below Ni)
- Ni and Pd (Pd is below Ni in the same column)
- Ni and Co (side by side in group VIII) ✓

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.

[ar-EG] الـ Ni والـ Co هما المتوقع يكونوا أشبه ببعض. الكتاب بيقول إن عناصر الـ group VIII بتتشابه أفقيًا أكتر من العناصر اللي تحتها في نفس الـ column.
## 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. Ten columns, eight group labels Give reason: the d-block contains ten vertical columns. **Because the d sublevel can take up to ten electrons.** Can you explain how eight group labels cover ten columns?



Chapter: Transition Elements (https://yaani.ai/en/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/en/lesson/chem-s3-en.lesson-te.d-block-groups