Explanation

 The maximum number of electrons in an atom is given by the formula:  

Total electrons = 2n²  

For n = 4:  

2(1² + 2² + 3² + 4²) = 2(1 + 4 + 9 + 16) = 2(30) = 60  

But this is a misunderstanding. Each shell holds:

- n=1: 2  

- n=2: 8  

- n=3: 18  

- n=4: 32  

So total = 2 + 8 + 18 + 32 = 60, but this is not per atom.  

If n = 4 is the maximum principal quantum number, then the 4th shell is being filled.  

The maximum number of electrons that can exist in the 4th shell is:  

2n² = 2(4)² = 32