Question Video: Determining the Number of Orbitals in an s Subshell Chemistry • Second Year of Secondary School

Video Transcript

How many orbitals are found in the s subshell?

Inside of an atom, electrons are found in various energy levels called shells. Each shell consists of one or more types of subshell, and each subshell consists of one or more atomic orbitals. The shells, subshells, and orbitals inside of an atom can be described using quantum numbers.

The principal quantum number 𝑛 represents the shell or energy level. 𝑛 can be any positive integer. The subsidiary quantum number 𝑙 represents the subshell. 𝑙 can be any integer from zero to 𝑛 minus one. Each subsidiary quantum number corresponds to a different type of subshell. A subsidiary quantum number of zero represents an s-type subshell, and a subsidiary quantum number of three represents an f-type subshell.

The orbitals that make up a subshell can be represented using the magnetic quantum number 𝑚 subscript 𝑙. 𝑚 subscript 𝑙 can be any integer from negative 𝑙 to positive 𝑙.

With all of this information in mind, let’s consider a shell with a principal quantum number of two. When the principal quantum number is two, the subsidiary quantum number can be either zero or one, which corresponds to an s-type subshell and a p-type subshell. When the subsidiary quantum number is zero, the magnetic quantum number can only be zero, indicating that this subshell only contains one orbital.

The lone orbital in an s-type subshell is called the s orbital and is spherical in shape. When the subsidiary quantum number equals one, the magnetic quantum number can be negative one, zero, or positive one, indicating that a p-type subshell contains three orbitals. These three orbitals — p 𝑧, p 𝑥, and p 𝑦 — consist of two regions of electron density and have a dumbbell-like shape.

Now that we have some background information, let’s return to the question. The question asks how many orbitals are found in an s-type subshell. We can see that an s subshell has a subsidiary quantum number of zero and contains only one orbital with a magnetic quantum number of zero. So the number of orbitals found in an s subshell is one.