Electronic Configurations of Atoms – Part 1 New!

We all learned in Basic Chemistry Course/Syllabus such as GCE-O Levels Chemistry that elements are found in the electron shell(s) and each shell can only accommodate up to a maximum of electrons.

This is what you might have learned previously:

• Shell 1 – Maximum of 2 Electrons
• Shell 2 – Maximum of 8 Electrons
• Shell 3 – Maximum of 8 Electrons
• Shell 8 – Maximum of 8 Electrons etc etc

As such, you would have heard previously that all elements can only hold 2 or 8 electrons in their valence shell – terms such as Duplet and Octet structure exists.

And the Electronic Configurations for Sodium (Ar=11) would be 2.8.1.

Now, when you come to doing Advanced Level Chemistry such as GCE A-Level Chemistry, we are going to learn a little more in depth, and perhaps what you learned in Basic Chemistry Course would not be so true now.

Let’s see what is new and additional!

Electron shells are also known as Principal Quantum Numbers i.e. first shell has principal quantum number = 1

Each electron shell consists of a number of Sub-Shells, labelled s, p, d or f.

The number of sub-shells in each shell equals to the shell number i.e. 1st shell has 1 sub-shell and 2nd shell has 2 sub-shells, etc

Each sub-shell contains a number of Orbitals. in which the electrons are placed. The number of orbitals in each sub-shell depends on the type of sub-shell as shown below:

Each of this orbitals can each take up 2 electrons.

Let’s take a look at an YouTube video now to have a better understanding on the connections between principal quantum shells, sub-shells, types of orbitals and the maximum number of electrons which can be occupied.

Length of video: 3.48 minutes

Direct video link: https://www.youtube.com/watch?v=xXdlAv-SO7c&t=1s

Stay tuned for next blogpost for Part 2 of Electronic Configuration of Atoms!

Related Articles:

• Atomic Structure: Number of Orbitals & Electrons in Quantum Shells
• Atomic Structure: 3 Rules of Writing Electronic Configurations of Atoms
• Electronic Configuration of Atoms – Part 2 New!
• Atomic Structure: Filling of Orbitals
• Sub-Atomic Particles of Atoms