I am a beginner trying to summarize what I've learned about:
- Energy Levels
- Subshells and
all at the high school level.
Unlike related threads, I'm going to try to:
- Define each word and state a few key properties of each.
- Highlight what is most important for beginners.
- Summarize all of that in a table.
Please let me know how I've done!
tl;dr Summary: Electrons move within orbitals which are in subshells which are in shells which are in atoms.
Shell aka Energy Level
Below atoms, shells are the largest grouping of electrons beginner chemists should care about, and among those, the innermost two shells are most important to beginners.
They correspond to periods (rows) on the periodic table of the element.
- In the 3rd period, all elements have 3 shells.
- In the 5th period, all elements have 5 shells.
- In the $n$th period, all elements have $n$ shells.
Generally speaking, the larger $n$ means:
- The shells are farther away from the nucleus and thus the electrons in it are less attracted to the nucleus.
- The shells can hold more electrons, i.e. an atom of that element requires more valence electrons to be stable.
Each shell consists of at least one subshell. Below atoms, this is the second largest grouping of electrons beginner chemists should care about.
There are 4 types of subshells: $s$, $p$, $d$, and $f$. For beginners, the $s$ and $p$ subshells are the most important.
The notation for shells and subshells:
- $1s^2$ means the 1st shell's $s$ subshell has 2 electrons in it.
- $4d^5$ means the 4th shell's $d$ subshell has 5 electrons in it
- $AB^X$ means the $A$th shell's $B$th subshell has $X$ electrons in it.
Note: This notation does not specify which orbital those electrons are in... but that info does not matter much to beginners.
An orbital is an actual path (probability distribution function, PDF) that either 1 or 2 electrons can be whizzing through at a time. This is the smallest grouping of electrons beginner chemists should care about. The math underlying that PDF is not critical for beginners.
Each subshell consists of at least one orbital.
THE BIG TABLE
Feel free to edit the table. :)