An element with the general electron configuration for its outermost electrons of `ns^2np^1` would be in which element group?

As you know, the periodic table is organized in blocks that correspond to the location of an element's highest-energy electrons.

http://chemistry.stackexchange.com/questions/7022/pair-of-analogous-periods-on-the-periodic-table

Elements that have their highest-energy electrons in the `s` orbital are located in the `s` block, elements that have their highest-energy electrons in a `p` orbital are located in the `p` block, and so on.

In your case, the electron configuration of the outermost electrons, i.e. valence electrons, in an atom looks like this

`n s^2 np^1`

Now, the highest-energy electron is located in a `p` orbital, more specifically in an `np` orbital, which is simply a `p` orbital located on the `n` energy level.

This places the element in the `p` block, which as you can see covers elements located in groups 13 to 18.

For any energy level, i.e. period in the periodic table, the first element located the `p` block is placed in group 13 and the last is placed in group 18.

The electron configuration for the outermost electrons of an element located in group 13 will thus be

`ns^2 np^1`

Since this matches the electron configuration given to you, you can say that this unknown element is located in group 13.

Similarly, you will have

• `ns^2 np^2 ->` an element located in group 14
• `ns^2 np^3 ->` an element located in group 15
• `ns^2 np^4 ->` an element located in group 16
• `ns^2 np^5 ->` an element located in group 17
• `ns^2 np^6 ->` an element located in group 18