If the following elements were to form ions, they would attain the same number of electrons as which noble gas?

elements: As, S, Na, Rb

noble gas: He, Ne, Ar, Kr

To work his question use the periodic table. There you can find any element. Its position on the table will tell you easily which configuration it will reach after losing or gaining electrons.

An neutral element has the same number of electrons (negative particles) and protons (positive particles). That is why it is neutral: negative charge = positive charge = = > zero net charge.

If an element gain electrons it will have an excess of negative charge (because the number of protons has not changed), forming what is known as an anion (a negative ion). If an element lose electrons it will have an excess of positive charge, forming a cation (a positive ion).

Then electronic configuration is the clue respond this question.

You need to use the periodic table.

1) As

It is the element number 33. It is in the group 15.

There are in total 18 groups. The noble elements are in the group 18.

When As, which is a non metal, gain 3 electrons (15 + 3 = 18) it will become an anion (negative ion) with the same number of electrons than the noble gas that is three places to its right in the periodic talbe, which is Kr.

The non metals only form cations, this is they only can gain electrons.

2) S

It is also a non metal.

It is in the group 16 of the periodic table. When it gains two electrons (16 + 2 = 18) it will become a negative ion (anion) with the same number of electrons than the noble gas two places to its righ in the periodic table, Ar.

3) Na

It is an alkalyne metal. Alkalyn metals are in the group 1 and row 3. Which means that they have only one electron in its valence shell. These elements can lose this valence electron to have the same number of electrons of the noble gas that is immediately before it (one row over it but in the group 18). In this case, that noble that is in the row 2 and group 18; it is Ne.

4) Rb is another alkalyne metal (group 1). It is in the row 5. Rb can lose its electron from the valence shell to become a cation (positive ion) with the same number of electrons than the noble gas (group 18) of the previous row (i. e. 4). The noble gas in the row 4 is Kr.