Strontium ground state electronic configuration

Write the complete ground-state electron configuration of the strontium atom, Sr, using the building-up principle. 

It is important to realize that the orbital ordering (5-58) used in the aufbau process is not fixed, but depends on the atomic number Z. The ordering in (5-58) caimot be blindly followed in all cases. For instance, the ordering shows that 5s fills before 4d. It is tme that element 38, strontium, has a 4p 5s 4d° configuration. But a later element, palladium, number 46, has 4p 4d °5s° as its ground state configuration. The effect of adding more protons and electrons has been to depress the 4d level more than the 5s level. 

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