Question

how many electrons are in this atom?

Explanation:

Step1: Recall electron - capacity rules

The s - orbital can hold a maximum of 2 electrons and the p - orbital can hold a maximum of 6 electrons. Each box in the diagram represents an orbital.

Step2: Count electrons in 1s

The 1s orbital has 2 electrons (since there is one box with two electrons).

Step3: Count electrons in 2s

The 2s orbital has 2 electrons (one box with two electrons).

Step4: Count electrons in 2p

The 2p sub - shell has 3 orbitals and each orbital has 2 electrons, so there are 6 electrons in 2p.

Step5: Count electrons in 3s

The 3s orbital has 2 electrons (one box with two electrons).

Step6: Sum up electrons

Add the electrons from each sub - shell: $2 + 2+6 + 2=12$.

Answer:

12