Atoms in period 1 of the periodic table have 1 or 2 valence electrons.

Here's why:

* Period 1 contains only hydrogen (H) and helium (He).

* Hydrogen has 1 electron, which is its valence electron.

* Helium has 2 electrons, both of which are valence electrons.

Remember, valence electrons are the electrons in the outermost energy level of an atom, and they are the ones involved in chemical bonding.