Question

which diagram is the correct electron dot diagram for the element helium?

Explanation:

Electron - dot diagrams (Lewis dot diagrams) show the valence electrons of an atom. Helium (\(He\)) has an atomic number of \(2\), so it has \(2\) electrons. The first electron shell (\(n = 1\)) can hold a maximum of \(2\) electrons. Since helium's valence shell (the only shell it has) is full with \(2\) electrons, in the electron - dot diagram, there should be \(2\) dots around the symbol \(He\).
Looking at the options:

• Option A: Has \(2\) dots (one above and one to the right of \(He\)). This is incorrect as the two electrons are paired in the same shell and should be represented as a pair (in the simplest sense for helium's electron - dot diagram, we consider the two valence electrons as a pair, usually shown as two dots adjacent to each other, but in some basic representations, two non - adjacent dots for helium is also a simplified way considering its closed - shell nature).
• Option B: Has \(2\) dots (one above and one to the right of \(He\)). Similar to option A.
• Option C: Has \(3\) dots, which is wrong because helium has only \(2\) electrons.
• Option D: Has \(2\) dots (one on each side), which is a valid representation of the two valence electrons of helium.
• Options E - H: Have more than \(2\) dots, which is incorrect as helium has only \(2\) electrons.

Answer:

D.