Question

Which of the following statements is correct?

a. The greatest probability of finding a `"1s"` electron is at the nucleus.
b. The size of an orbital is directly proportional to its principal quantum number,
c. A `"3p"` orbital can hold three electrons.
d. A `"2s"` orbital is different from a `"1s"` orbital because the `"2s"` orbital requires more energy for the electrons to fill it.

Answer 1

d. `"2s"` is different from `"1s"` because the `"2s"` requires more energy for the electrons to fill it.

Explanation:

a. This option is wrong.

The probability of finding electrons of any orbital in the nucleus is zero.

Here are the probability plots for `"1s, 2s"`, and `"3s"` orbitals.

(From Quora)

Notice that the probability is zero at the nucleus (0 pm).

b. This option is wrong.

The sizes of the orbitals are roughly proportional to `n^2`, where `n` is the principal quantum number.

Thus, the `"2s"` orbital is about four times as big as a `"1s"` orbital.

c. This option is wrong.

The Pauli Exclusion Principle states that no orbital can hold more than two electrons.

d. This option is correct.

`"2s"` is different from `"1s"` because the `"2s"` requires more energy for the electrons to fill it.

A `"2s"` orbital is bigger than a `"1s"` orbital, and it takes energy to move an electron further away from the attraction of the nucleus.

Thus, a `"2s"` orbital is higher in energy than a `"1s"` orbital.