Predict the number of valence electrons for each element based on its location in the periodic table of elements.
barium = lead = bismuth = potassium =

Barium= Group 2, 2 valence electrons

Lead= Group 14, 4 valence electrons

Bismuth= Group 15, 5 valence electrons

Potassium= Group 16, 6 valence electrons

Explanation:

When you move down, from left to right, the groups on the periodic table, the valence electrons increase.

Ex: Hydrogen is in Group 1, so it has 1 valence electron.

Now for the elements with double digits, like 18, then you take the second number.

Ex: Helium is in Group 18, so it has 8 valence electrons.