The Lewis dot structure for water is shown in the attached image. Here are the steps for drawing a Lewis dot structure:
1. Determine the total number of valence electrons:
hydrogen: 2 atoms X 1 valence electron = 2 valence electrons
oxygen: 1 atom X 6 valence electrons = 6 valence electrons
total: 2 + 6 = 8 valence electrons
2. Arrange the atoms:
The least electronegative atom usually goes in the center, but in this case oxygen is the center atom because a hydrogen atom can only have one pair of electrons.
3. Arrange the electrons so that each atom has a complete octet:
Hydrogen is an exception to the octet rule because it has a complete energy level with only two electrons. Each hydrogen atom shares a pair of electrons with the oxygen atom. The oxygen atom has two shared and two unshared pairs for a total of eight electrons, a complete octet.