I assume you are filling up the electron shells using the rules of chemistry and finding it breaks down :-)
The rules start getting very tested as the atoms get very big because they are simplifications of a much more complicated process.
Like newtons laws they are a useful simplification but not an exact solution.
I understand you are at high school Gan so that may be enough explaination, if you are desperate to know I will give you this QM reference PDF and you will need to read up on Pauli exclusion principle (
http://storage.canalblog.com/63/76/292736/65665258.pdf)
Almost all periodic tables of the chemical elements are between 96 % and 100 % in accord with quantum mechanics. Three elements only do not fit correctly into the official tables, in disagreement with the Pauli exclusion principle. In order to ensure coherence, it is put forward to place helium beside hydrogen into the s-block instead of the p-block. Lutetium and lawrencium pertain to the d-block of the transition metals and should not be in the f-block with the rare earths or the actinoids. With these slight modifications, the IUPAC table becomes entirely quantum mechanics consistent.
There are valid arguments around our 3 elements that don't match but the arguments have not been scientifically settled.
So to teach it properly at high school level would teaching Quantum Mechanics and for most of your fellow students that level of science would be difficult and have no benefit in life for them.
