- Cr(24): 1s2 2s2 2p6 3s2 3p6 4s1 3d5
Half filled orbitals are more stable because of symmetrical distribution of electrons and exchange energy is maximum.
- $\Delta\text{V}=50\times\big[(100-99.99)\%\big]$
$=50\times\frac{0.01}{100}=50\times10^{-4}$
$=5\times10^{-3}\text{ms}^{-1}$
$\Delta\text{x}.\Delta\text{V}=\frac{\text{h}}{4\pi\text{m}}$
$\Delta\text{x}\times5\times10^{-3}\text{ms}^{-1}=\frac{6.6\times10^{-34}\text{Js}}{4\times3.142\times9\times10^{-31}\text{kg}}$
$\Rightarrow\Delta\text{x}=\frac{6.6\times10^{-34}\text{Js}}{4\times3.142\times9.1\times10^{-31}\text{kg}\times5\times10^{-3}\text{ms}^{-1}}$
$=1.154\times10^{-2}\text{m}$
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Scandium (Atomic number 21) is the element in which filling of 3d orbitals starts.