Why Cr and Cu have abnormally higher 2nd ionisation energy

Explanation

To understand why chromium (Cr) and copper (Cu) have abnormally high second ionization energies, we need to analyze their electronic configurations and the stability associated with them.

### Step-by-Step Solution:

1. **Definition of Ionization Energy**:
- Ionization energy is the energy required to remove an electron from an isolated gaseous atom. The first ionization energy refers to the removal of the first electron, while the second ionization energy refers to the removal of the second electron.

2. **Electronic Configuration of Chromium (Cr)**:
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