Electronic Structure: Electron Spin - Online Tutor, Practice Problems & Exam Prep

According to the Pauli exclusion principle, an orbital can hold a maximum of two electrons with opposite spins. Each electron's spin is represented by arrows: one pointing up (spin +1/2, clockwise) and one pointing down (spin -1/2, counterclockwise). This concept is crucial for understanding electron configuration and the behavior of atoms in chemical reactions, influencing properties such as atomic radius and bonding characteristics. Mastery of these principles aids in grasping more complex topics in chemistry, including molecular geometry and reaction mechanisms.

Electronic Structure: Electron Spin Concept 1

Now, an orbital can hold a maximum of 2 electrons that have opposite spins according to the Pauli exclusion principle. It states that no two electrons found within an orbital can have the same electron spin. So, one has to spin up and one has to spin down. When we talk about this electron spin, it deals with the rotational spin of an electron inside an atomic orbital. We begin by filling an orbital with an electron that points up, followed by the next one pointing down. To depict electrons within an orbital, we use arrows; one would point up and one would point down, indicating they have opposite spins inside the same orbital.

Note that the electron that points up has an electron spin value of 1/2, and since it's pointing up, it's spinning clockwise. Conversely, an electron pointing down has an electron spin value of -1/2, which also indicates that it has a counterclockwise spin. So, just remember, plus one half is synonymous with clockwise, and negative a half is synonymous with counterclockwise in relation to an electron spin.

Electronic Structure: Electron Spin Example 1

Here it says to provide the n value, sub shell letter, and electron spin for the highlighted electron in a third principal level. Alright. So here when we're talking about the third principal level, we're talking about the energy level or shell number. Thus, this means that n equals 3 because, remember, energy level, shell number, principal level, all referring to the n value. That means the answer is either b or d.

Next, we have an image here of 3 orbitals. You have to think about which sub shell letter has 3 orbitals. Remember, s only has 1, p is the one that has 3, d has 5. So, we're dealing with p. Hence, the sub shell letter is p. So far, it's still between options b or d.

Now we look at the electron within that particular orbital. Which way is it pointing? Is it pointing up or is it pointing down? We can see that the electron that's highlighted is pointing down. That means that its electron spin would be minus a half. So, that would mean that option would be our correct answer.

Which of the following can represent the highlighted electron in a set of 5d orbitals.

• A. n = 5, subshell = f, electron spin = –1/2
• B. n = 4, subshell = s, electron spin = –1/2
• C. n = 5, subshell = d, electron spin = +1/2
• D. n = 5, subshell = p, electron spin = –1/2
• E. n = 5, subshell = s, electron spin = +1/2