Advanced electronic configuration Done by: Su Di Yang (8)

Introduction to advanced electrical configuration Our current model of the atom no longer involves electrons whirling through circular orbits. Rather, we now know we cannot pinpoint an electron’s exact location. This is because of the Heisenberg uncertainty principle. An electron cannot be pinpointed as the photon striking it will cause it to change momentum and position, so you will never be able to find an exact location of an electron (until the day you happen to find an observable particle smaller than an electron)

Electronic configuration naming As we know, electrons occupy certain energy levels around the atom. These energy levels are called shells. Electrons jump to higher energy levels when provided with energy, but will automatically drop back down to the lowest energy level possible. These energy levels are named 1, 2, 3, 4, 5, 6, 7, 8 and so on. (So far the heaviest element discovered ever has only 7 shells of electrons)

Electronic configuration naming (continued) Each of these orbitals can be further subdivided into sub-orbitals. They have similar energy levels but orbit the atom differently. So far the most common sub-orbitals are s, p, d and f. So to name the possible location the atom resides in, you state its shell number followed by its sub-orbital number i.e. 1s,2p,3d and stuff like that.

Number of electrons sub-orbitals can carry Each sub-orbital (s, p, d and f) can hold a certain number of electrons. The s sub-orbital can hold only 2 electrons (please note from hereon the number of electrons a sub-orbital can hold will automatically mean the maximum number of electrons unless stated otherwise). The p sub-orbital can hold 6 electrons. The d sub-orbital can hold 10 electrons The f sub-orbital can hold 14 electrons.

Number of electrons sub-orbitals can carry (continued) One might notice that the number of electrons each sub-orbital holds is always an even number. This is due to the Aufbau principle and the Pauli Exclusion principle.

Pauli Exclusion Principle All electrons have a property known as spin. This spin can take the form of up or down. The Pauli Exclusion Principle states that no two baryons can exist in the same quantum state together. In short, two electrons with the same spin cannot be paired together.

Aufbau Principle The Aufbau principle makes use of the Pauli exclusion principle (somewhat). It states that each sub-orbital consists of a number of blocks, each block can hold two electrons (Pauli Exclusion Principle). That in a nutshell is why all electron sub- orbitals can contain an even number of electrons.

Aufbau Principle (continued) The Aufbau principle also tells us the supposed order in which the sub-orbitals are filled up. To all ye fellow classmates impaired with severe complicated-diagram-phobia, please refrain from viewing the following slides.

Aufbau Principle (COMPLICATED DIAGRAMS!!!!!!!!!!!!!!!!!!!!!) Well, not really Provided all those with severe complicated- diagram-phobia sufferers have been evacuated, let’s continue. Take a look at this diagram This diagram is all the sub-orbitals in seven shells. To find the order in which the electrons are filled, draw diagonal lines towards the bottom left. 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f

Aufbau principle (yes, continued again) One then reads down the arrows and from the top arrow progressively to the bottom one. So from the previous diagram, we get 1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5s,4d,5p,6s,4f,5 d,6p,7s and so on. However, there are some violations of this rule ( though not enough to make it completely useless)

The Periodic Table The periodic table also plays a part in categorising sub-orbital filling as shown below:

THE END