Step 1: add electrons to fill the 1s subshell (maximum of 2 electrons), when this is full, go to step 2. Step 2: add electrons to fill the 2s subshell (maximum of 2 electrons), when this is full, go to step 3. Step 3: add electrons to fill the 2p subshell (maximum of 6 electrons), when this is full, go to step 4. Step 4: add electrons to fill the 3s subshell (maximum of 2 electrons), when this is full, go to step 5. Step 5: add electrons to fill the 3p subshell (maximum of 6 electrons), when this is full, go to step 6. Step 6: add electrons to the 4s subshell (maximum of 2 electrons), when this is full, go to step 7. Step 7: add electrons to the 3d subshell (maximum of 10 electrons), when this is full, go to step 8. Step 8: add electrons to the 4p subshell (maximum of 6 electrons), when this is full, go to step 9. etc
So for Cu would be: 1s^22s^22p^63s^23p^63d^9
Ag would be: 1s^22s^22p^63s^23p^63d^104s^24p^64d^105s^1
Au would be: 1s^22s^22p^63s^23p^63d^104s^24p^64d^105s^25p^64f^145d^106s^1
