(a) the number of electrons that can fill the first four shells

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(b) atomic orbitals, including:

              (i) as a region around the nucleus that can hold up to two electrons, with opposite spins

              (ii) the shapes of s- and p-orbitals

              (iii) the number of orbitals making up s-, p- and d-sub-shells, and the number of electrons that can fill s-, p- and d-sub-shells

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(c) filling of orbitals:

              (i) for the first three shells and the 4s and 4p orbitals in order of increasing energy

              (ii) for orbitals with the same energy, occupation singly before pairing

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(d) deduction of the electron configurations of:

              (i) atoms, given the atomic number, up to Z = 36

              (ii) ions, given the atomic number and ionic charge, limited to s- and p-blocks up to Z = 36.