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 1: Analyze the Given Ionization Energies
We have the following successive ionization energies (in kJ/mole):
- 1st Ionization Energy (IE1) = 800
- 2nd Ionization Energy (IE2) = 900
- 3rd Ionization Energy (IE3) = 925
- 4th Ionization Energy (IE4) = 25356
- 5th Ionization Energy (IE5) = 32456

### Step 2: Identify the Pattern in Ionization Energies
The first three ionization energies (800, 900, and 925 kJ/mole) are relatively low and close in value, indicating that it is relatively easy to remove these electrons. This suggests that these electrons are likely valence electrons.

### Step 3: Observe the Large Jump in Ionization Energy
The fourth ionization energy (IE4 = 25356 kJ/mole) shows a significant increase compared to the previous three. This large jump indicates that the fourth electron is much more difficult to remove, suggesting that it is being removed from a more stable, inner electron shell.

### Step 4: Determine the Number of Valence Electrons
Since the first three ionization energies are low and the fourth is very high, we can conclude that the atom has three valence electrons. The removal of these three electrons is relatively easy, while removing the fourth electron requires a significantly higher amount of energy due to it being from a filled inner shell.

### Conclusion
Thus, the valency of the atom is 3, as it can lose three electrons to achieve a stable electronic configuration.

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

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