Electronic Structure: Shells: Study with Video Lessons, Practice Problems & Examples

In atomic theory, the principal quantum number (n) indicates the energy level and size of an atomic orbital, with values ranging from 1 to infinity. Each period in the periodic table corresponds to a shell, with currently seven known rows. As technology advances, new elements may be discovered, potentially leading to additional rows. Understanding the relationship between shell numbers and periodic table rows is crucial for grasping atomic structure and the dynamic nature of elements.

Electronic Structure: Shells Concept 1

Now recall a shell, which uses the variable \( n \), is a grouping of electrons surrounding the nucleus that ties into their potential energy, so their energy of position. Now we're gonna say as the value of \( n \) increases, then both the size and energy level of an atomic orbital will increase. And we're going to say here that the energy levels, also the shell numbers of an atom can be tied to the periods or rows of the periodic table. So here we have an atom. This atom has its nucleus, and we can see that I have given it 7 shells. Right? Remember, each black orbital represents a shell. 1st shell all the way to the 7th shell here. We'll realize here that the shells of an atom are directly related to the periods or row of the periodic table. So remember, your periods or rows of periodic table go from left to right. So this is row 1, so this is shell 1, shell 2, 3, 4, 5, 6, and 7. Now currently there are 7 rows in the periodic table, but what you need to understand about the periodic table is that it is dynamic. A lot of these elements found in the 7th row of the periodic table have been discovered within the past decade. A bunch of these here were formally named in the past 10 years. So theoretically, as we move to new planets, as we explore more of the earth, as our technology gets more advanced, we're gonna create and find new elements. So eventually, there's gonna be an 8th row of elements, and then a 9th row, and so on and so forth. We're only limited by our imagination and our ingenuity. The number of elements can continuously increase again as we discover them and as we create them. Now we're gonna say because of this, the limitation of the \( n \) value is that it must be an integer, remember, whole number, from 1, because the smallest number shell can be is 1, to infinity. There's an infinite number of possible shells. Again, we're only limited by our resources, our imagination, and our ingenuity. We can create new elements with 10 shells, 12 shells, and so on. So keep in mind the relationship between rows of the periodic table and shell numbers of an atom and realize the limitation of it is that it can be any number from 1 to infinity.

Electronic Structure: Shells Example 1

Of the following, is a possible value for the shell of an atom? Remember, we talked about the only real limitation when it comes to the shell number of an atom is that it's connected to the rows of the periodic table, and because of that it can be any integer from 1 to infinity. So, negative 3 can't be an exact number because that's less than 1. Same thing with negative 4. It has to be a number from 1 to infinity, so 0 is out, and e is out. So n being 2, meaning the second shell of an atom, is a possible value for n. Right? So here, the only option that works is option d.

Which of the following shell number values is a possible value for the element highlighted?

• A. n = 10
• B. n = 4
• C. n = 6
• D. n = 7

Which electron possesses the lowest possible energy from the image provided?

• A. A
• B. B
• C. C
• D. D
• E. E

Here’s what students ask on this topic:

What is the principal quantum number (n) and how does it relate to the energy levels of an atom?

The principal quantum number (n) is a fundamental concept in atomic theory that indicates the energy level and size of an atomic orbital. It is denoted by the variable n and can take on integer values starting from 1 and extending to infinity. As the value of n increases, both the size and energy level of the atomic orbital increase. This means that electrons in higher energy levels (higher n values) are further from the nucleus and possess more potential energy. The principal quantum number also correlates with the periods or rows of the periodic table, where each period corresponds to a specific shell number. For example, elements in the first period have electrons in the n=1 shell, while elements in the second period have electrons in the n=2 shell.

How are the shells of an atom related to the periods of the periodic table?

The shells of an atom are directly related to the periods (rows) of the periodic table. Each period corresponds to a specific shell number, denoted by the principal quantum number (n). For instance, the first period corresponds to the n=1 shell, the second period to the n=2 shell, and so on. Currently, there are seven known periods in the periodic table, which means there are seven known shells. As new elements are discovered or created, additional periods (and thus additional shells) may be added. This relationship helps in understanding the arrangement of electrons around the nucleus and the overall structure of the atom.

Can the number of shells in an atom be infinite?

Yes, theoretically, the number of shells in an atom can be infinite. The principal quantum number (n) can take on any integer value from 1 to infinity. This means that as new elements are discovered or created, additional shells can be added. Currently, we know of elements with up to seven shells, corresponding to the seven periods of the periodic table. However, as technology advances and new elements are found or synthesized, it is possible to have elements with more than seven shells. The only limitation is our current resources, imagination, and ingenuity.

Why is the periodic table considered dynamic?

The periodic table is considered dynamic because it evolves as new elements are discovered or synthesized. Over the past decade, several elements in the seventh period have been formally named and added to the table. As scientific research progresses and technology advances, it is likely that more elements will be discovered, leading to the addition of new periods and shells. This dynamic nature reflects the ongoing exploration and understanding of atomic structure and the potential for discovering new elements beyond the current known ones.

What is the significance of the relationship between shell numbers and periodic table rows?

The relationship between shell numbers and periodic table rows is significant because it helps in understanding the arrangement of electrons in an atom. Each row (period) of the periodic table corresponds to a specific shell number, denoted by the principal quantum number (n). For example, elements in the first row have electrons in the n=1 shell, while elements in the second row have electrons in the n=2 shell. This relationship provides a systematic way to determine the electron configuration of elements and predict their chemical properties. It also highlights the periodic nature of elements, where elements in the same column (group) have similar valence electron configurations and exhibit similar chemical behavior.