Atomic Structure - Energy Level

In the study of atomic structure, there is a certain set of ground rules (please refer to lecture material for basics) which we make use to fill electrons. These rules are formulated because we fill electrons in shells, subshells and orbital which are of lower energy level first.

The following diagram illustrates the three main orbital which we are required to know at the GCE "A" Level curriculum. Of these three orbitals, the s-orbital has the lowest energy while the d-orbital has the highest.

This electrostatic attraction will result in the s-orbital to be of lower energy. This is abit perplexing, but we need to rationalise that electrostatic attraction is a form of potential energy (PE).

By definition, potential energy is a negative number and the weakest potential energy is at infinity. In that case, PE = 0. Hence, a greater electrostatic attraction will result in a larger numerical value of PE, but because of the definition of PE, the energy is lowered.
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Article written by Kwok YL 2009.}

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