The nucleus of an atom of an element contains 17 protons. What element is it? What is the structure of the electron shells of its atoms?

The number of protons is always equal to the number of electrons. It follows from this that the nucleus of an atom contains 17 electrons.
The number of electrons is equal to the ordinal number of the element in the periodic table.
Now you need to turn to the table. At number 17 is the element – chlorine (Cl).
The structure of the atom by energy levels:
1) At the first level there are two paired electrons on the S sublevel;
2) At the second level, all electrons are also paired. Of these, two are at the S sublevel and six are at the P sublevel;
3) At the third level, there are two paired electrons at the S sublevel. There are five electrons on the P sublevel, four of which are paired and one without a pair.