# Why do some people call (H_3C)_4C "neopentane" instead of "dimethyl propane"?

${\left({H}_{3} C\right)}_{4} C$, has a molecular formula of ${C}_{5} {H}_{12}$, i.e. it is an isomer of pentane. We could call this $\text{dimethylpropane}$ (am I correct in omitting the numbers, i.e. NOT stating $\text{2,2-dimethylpropane}$?), but I think it is easier to call this $\text{neopentane}$. Such so-called trivial names are recognized by most chemists, and most schemes of nomenclature.
The $\text{neopentyl group}$ is ${C}_{5} {H}_{11}$, e.g. $\text{neopentyl lithium}$ $\equiv$ Li^(+)""^(-)CH_2C(CH_3)_3; likewise the $\text{neosilyl group}$ is ${\left({H}_{3} C\right)}_{3} S i C {H}_{2}$, i.e. ${C}_{4} S i {H}_{11}$..............