The Aufbau Principle is an essential rule in chemistry. It helps us figure out the electron arrangement within an atom in a specific order. According to this principle, electrons fill atomic orbitals of the lowest energy first before moving on to higher energy levels. This filling order is often remembered by the sequence: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, and so forth.
The Aufbau principle ensures that electrons are added in a way that creates the lowest possible energy configuration for the atom.
- For Strontium (Sr), we start filling from the 1s orbital and continue according to the order, resulting in its electron configuration: 1s虏 2s虏 2p鈦 3s虏 3p鈦 4s虏 3d鹿鈦 4p鈦 5s虏.
- For Tin (Sn), similarly, we fill up to 5p虏, giving: 1s虏 2s虏 2p鈦 3s虏 3p鈦 4s虏 3d鹿鈦 4p鈦 5s虏 4d鹿鈦 5p虏.
This principle is vital to correctly assigning electrons to their respective orbitals based on energy levels.