Maximum value of $n+l+m$ for the last unpaired electron in an element present in 17th group and 4th period of periodic table:

For 17th group and 4th period of periodic table the value of the principal(n),azimuthal(l) and magnetic quantum number (m) is 4,1 and +1.

$n=4$

$l=1$

 $m=+1$

The maximum value of $n+l+m$ for the last unpaired electron in an element is found by the calculation,

$$\begin{gathered} \mathit{=}n+l+m \\ =4+1+1 \\ =6 \end{gathered}$$

Hence he maximum value of $n+l+m$ is 6.