Question

How can you determine the electron configuration without a periodic table?

Answer 1

For that we have to use the aufbau principle

Explanation:

We have to start from 1s and gradually move with the arrows indicated in the diagram above.

For example, writing the electronic configuration of Fe(28)

`1s^2,2s^2,2p^6,3s^2,3p^6,4s^2,3d^8`

we move according to the diagram i.e 1s then 2s then 2p then 3s and so on.

I recommend that you memorize the aufbau principle. Once you memorize it, you don't need anything else except the atomic number of the element to write its electronic configuration.