(N/A) The oxidation states of elements are determined by their electronic configuration,specifically the number of electrons in the outermost shell and the stability of the resulting configuration.
$1$. Non-transition elements: Consider Nitrogen $(Z=7)$ with configuration $[He] 2s^{2} 2p^{3}$. It can show oxidation states like $-3$ (by gaining $3$ electrons to complete the octet) or $+5$ (by losing $5$ valence electrons).
$2$. Transition elements: Consider Manganese $(Z=25)$ with configuration $[Ar] 3d^{5} 4s^{2}$. Due to the availability of both $4s$ and $3d$ electrons,it exhibits variable oxidation states ranging from $+2$ to $+7$. The $+2$ state arises from the loss of $4s^{2}$ electrons,while higher states involve the progressive loss of $3d$ electrons,reaching stability at $+7$ where the $3d$ subshell becomes empty.