Orbitals

By which pattern do electrons fill orbitals?

Figure 28.5: The Aufbau principle.

The electrons fill orbitals according to the Aufbau Principle as seen above in Figure 28.5. For example, Na is $1s^{2} 2s^{2} 2p^{6} 3s^{1}$. Below you will see the usefulness of using Noble Gases to make conventional notation shorter.

What are exceptions to this pattern of filling?

Copper (Cu) and Chromium (Cr) arranged in the middle and end of the transition elements, respectively, which do not fill according to Hund's rule:

Table 28.4: Magnetic ($m_{l}$) and spin quantum numbers ($m_{s}$).

	Expected	Observed
Cu	$[Ar]4s^{2}3d^{9}$	$[Ar]4s^{1}3d^{10}$
Cr	$[Ar]4s^{2}3d^{4}$	$[Ar]4s^{1}3d^{5}$

Note [Ar] is shorthand for the electronic configuration of Argon, which by definition has a ``full'' complement of $e^{-}$ and is a useful way of using Noble Gases to document electron configuration.

How do the $s$, $p$, $d$ and $f$ orbitals correlate to the periodic table?

Figure 28.6: $s$, $p$, $d$ and $f$ orbital distribution on the periodic table.

What are the general shapes of $s$ and $p$ orbitals?

Figure 28.7: Orbital geometries of $s$ and $p$ orbitals.