Neon has 10 protons and 10 electrons. How are the electrons filled in the energy levels?
In a simple model of atomic shells, the shells fill in the following sequence:
Since there are 10 electrons, the first two shells are filled (2 + 8 = 10 electrons)
A more complex model considers each orbital. Orbitals fill in the order 1s,1p,2s,2p.....
s orbitals hold 2 electrons, and p orbitals hold 6 electrons. We fill these orbitals until we have included all 10 electrons.
The first s orbital holds 2 electrons
The first p orbital holds 6 electrons
The second s orbital holds 2 electrons
2 + 6 + 2 = 10 electrons