# Why several oxidation states

> Vanadium's gradual climb


## Objectives

- State that the main transition elements have several oxidation states, while representative metals have one.
- Read the book's chart of vanadium's successive ionization potentials (also called ionization energies) (648, 1346, 2858, 4643, 6523 kJ/mol).
- Explain why: the 4s and 3d electrons are close in energy and are lost in sequence, so the ionization potentials increase gradually.

## 1. Electronic configurations and oxidation states




## 2. Jump or ramp?

Predict: when vanadium moves on from 4s to 3d electrons, what happens to the energy needed?

- A gradual rise, with no huge jump ✓
- It drops: 3d electrons are easier to remove
- A huge jump, like sodium's

Vanadium's 4s and 3d electrons are in sublevels close in energy, so its successive ionization potentials increase gradually, with no huge jump like sodium's.

[ar-EG] الـ 4s والـ 3d بتوع الـ vanadium قريبين من بعض في الطاقة، فالـ successive ionization potentials بتزيد بالتدريج، من غير قفزة كبيرة زي اللي عند الـ sodium.
## 3. One state or several?

Book point 5: the main transition elements have several oxidation states. Representative metals have one. Representative metals vs transition metals (V and Mn from the book's table, p.8) Why the difference? The answer is in the successive ionization potentials.


## 4. Strip vanadium, read the cost

Remove vanadium's electrons one at a time. Each step shows the book's ionization potential. electrons removed V: $4s^2\ 3d^3$ $\ce{V+}$: $4s^1\ 3d^3$ energy for electron 1 $\ce{V^{2+}}$: $4s^0\ 3d^3$ energy for electron 2 $\ce{V^{3+}}$: $4s^0\ 3d^2$ energy for electron 3 $\ce{V^{4+}}$: $4s^0\ 3d^1$ energy for electron 4 $\ce{V^{5+}}$: $4s^0\ 3d^0$ energy for electron 5 The book's chart for vanadium Successive ionization potentials of vanadium, kJ/mol (book p.10)


## 5. A gradual rise

Sodium jumps at the 2nd electron; vanadium climbs step by step Vanadium loses electrons from 4s and 3d in sequence. These two sublevels are close in energy. So its ionization potentials increase gradually. No huge jump stops it, so several oxidation states can form.


## 6. Which metal is it?

Metal X: 738, 1451, 7733 kJ/mol. Metal Y: 659, 1310, 2653, 4175 kJ/mol. Which is a transition metal with several oxidation states?

- X
- Y ✓
- Neither: the values are too large
- Both: each list rises

X (magnesium): a big jump after the 2nd electron, so only +2. Y (titanium): a gradual rise, so several states.

[ar-EG] الـ X (الـ magnesium): فيه قفزة كبيرة بعد الـ electron التاني، عشان كده +2 بس. الـ Y (الـ titanium): زيادة بالتدريج، فبيبقى ليه أكتر من state.
## 7. Build the exam answer

Give reasons: the main transition elements have several oxidation states. Put the answer in order.


## 8. Summary

Main transition elements have several oxidation states; representative metals (Na, Mg, Al) have one. They lose 4s and 3d electrons in sequence, and these are close in energy. So the ionization potentials increase gradually: vanadium 648, 1346, 2858, 4643, 6523 kJ/mol. Book point 5 (p.10): why main transition elements have several oxidation states The atom loses electrons from **4s and 3d in sequence**, which are **close in energy**. So the **ionization potentials increase gradually**, and several oxidation states form. Back to the hook: can you explain why vanadium shows no huge jump between its 4s and 3d electrons?



Chapter: Transition Elements (https://yaani.ai/ar/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/ar/lesson/chem-s3-en.lesson-te.multiple-oxidation-states