Drawing the Lewis Structure for BeH2

Viewing Notes:

  • The BeH2 Lewis structure is similar to BeF2 and BeCl2 except that F and Cl are in Group 7 and have 7 valence electrons.
  • Beryllium (Be) doesn't need 8 valence electrons to have an octet (Be often only needs 4).
  • If you're not sure you have the best Lewis structure for BeH2 you can calculate the formal charges. You'll find the Be in BeH2 only has 4 valence electrons.
  • For the BeH2 Lewis structure there are a total of 16 valence electrons available.
  • Hydrogen (H) only needs 2 valence electrons for a full outer shell.

Transcript: Hi, this is Dr. B. Let's do the Lewis structure for BeH2. On the periodic table, Beryllium has 2 valence electrons and Hydrogen has 1, but we have 2 Hydrogens, so we have a total of 4 valence electrons. Put Beryllium here, and Hydrogen will go on the outside. So we've got 4 valence electrons. We'll put 2 between atoms to form chemical bonds: 2, 4. Actually, we've used all our valence electrons at this point. Let's check and see if we have full outer shells. Hydrogen only needs 2, so both of those Hydrogens are fine. Beryllium has 4, but Beryllium is an exception: it doesn't necessarily need 8 valence electrons. So with that, we've done the Lewis structure for BeH2. This is Dr. B., and thanks for watching.