In earlier blogpost, we have discussed how electronic configurations are different from Basic Chemistry (such as GCE O-Levels) and Advance Level Chemistry (such as GCE A-Levels).
Today we are going to continue where we left off.
Electronic configuration refers to the arrangement of electrons in atoms and they follow certain rules:
1. Each orbital can hold a maximum of 2 electrons
2. Electrons always go into an empty orbital with the lowest energy first
3. In a sub-shell, electrons stays as far apart as possible – thus 2 electrons will go into 2 different orbitals of same energy level, rather than fitting together into 1 orbital
4. Electrons always have a spin, they either spin up ↑ or down ↓
This is where you learn something known as Box-Diagram.
Say for Sodium (Z=11), we will have the following Electronic Configuration based on the rules above.
We can simplified it to 1s22s22p63s1.
Useful way to remember the order of filling orbitals with electrons:
1s2s3s3p4s3d4p5s
Hope you find the above useful. Drop me a comment, i would love to hear from you.