What is the valency of an atom if its successive ionisation energies respectively are `800,900,925,25356,32456`KJ/mole?

Options

A. 3
B. 4
C. 5
D. 6

Answer

To determine the valency of an atom based on its successive ionization energies, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Ionization Energies**:
We are given the following successive ionization energies:
- First Ionization Energy (IE1) = 800 kJ/mol
- Second Ionization Energy (IE2) = 900 kJ/mol
- Third Ionization Energy (IE3) = 925 kJ/mol
- Fourth Ionization Energy (IE4) = 25356 kJ/mol
- Fifth Ionization Energy (IE5) = 32456 kJ/mol

2. **Analyze the Ionization Energies**:
The first three ionization energies (800, 900, and 925 kJ/mol) are relatively low and close to each other. This suggests that it is relatively easy to remove the first three electrons from the atom.

3. **Identify the Large Jump**:
There is a significant increase in the fourth ionization energy (25356 kJ/mol). This large jump indicates that removing the fourth electron requires a much higher amount of energy, suggesting that the atom has achieved a stable electron configuration after losing three electrons.

4. **Determine the Valency**:
Since the atom can lose three electrons relatively easily (as indicated by the first three ionization energies), and the fourth electron removal requires a much larger amount of energy, we conclude that the valency of the atom is 3. This means the atom can lose three electrons to achieve a stable noble gas configuration.

### Final Answer:
The valency of the atom is **3**.

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