Question

How many electrons can the fourth energy level hold according to Niels Bohr?

Answer 1

The fourth energy level has 18 electrons.

The fourth energy level of the periodic table includes the 4s 3d and 4p orbitals.

The 4s orbital holds 2 electrons
The 3d orbital holds 10 electrons
and
The 4p orbital holds 6 electrons.

There is a 4d orbital with 10 electrons which coincides with the 5th energy level of the periodic table.

There is also a 4f orbital with 14 electrons, but this coincides with the 6th energy level of the periodic table.

I hope this was helpful.
SMARTERTEACHER

Answer 2

`32` electrons.

Explanation:

(This was originally a comment.)

@Brian M. wrote that it was `18` electrons, but here are my reasons for it being `32` electrons instead.

Method 1:
The expression that we can use to calculate the maximum number of electrons given energy level is `2n^2`, with `n` being the energy level.
The fourth energy level, therefore, should have `2*(4)^2 = 2*16 = 32` electrons.

Method 2:
The fourth energy level doesn't necessarily equate to the fourth period in the periodic table.

The maximum number of electrons to be gained in the fourth period is `18`, because we have:

• `2` electrons from the `4s` orbital series;
• `10` electrons from `3d` orbital series; and
• `6` electrons from `4p` orbital series.

`2 + 10 + 6 = 18` electrons.

However, this doesn't include other fourth energy level orbitals, like `4d` and `4f`. It also includes the `3d` orbitals, which is in the third energy level.

The fourth energy level, however, is composed of the `4s, 4d, 4p,` and `4f` orbital series—the `4` in front means that it's in the fourth energy level.

That would give us:

• `2` electrons from the `4s` orbital series;
• `6` electrons from `4p` orbital series;
• `10` electrons from `4d` orbital series; and
• `14` electrons from `4f` orbital series.

`2 + 6 + 10 + 14 = 32` electrons.