# How many valence electrons does O have?

This means that it's outer energy level contains six valence electrons. To find valence electrons using the periodic table, look at the group/family (column) number. If it is in group 1 or 2, the group number is the number of valence electrons. If it is in group 13-16, subtract 10. If it is in the middle section (transition metals, Lanthanoids, or Actinoids), the rules are not so clear-cut. Luckily Oxygen ($O$) is in group 16, so it has 6 valence electrons.