The number of valence electrons in each group of the periodic table can be determined by looking at the group number. Here's a breakdown of the valence electrons in each group:
Group 1 (Alkali metals): 1 valence electron Group 2 (Alkaline earth metals): 2 valence electrons Group 13: 3 valence electrons Group 14: 4 valence electrons Group 15: 5 valence electrons Group 16: 6 valence electrons Group 17 (Halogens): 7 valence electrons Group 18 (Noble gases): 8 valence electrons (except for helium, which has 2 valence electrons)
It's worth noting that for the transition metals, the valence electrons can vary, and their electron configurations are more complex. The valence electrons for these elements may involve the outermost s and d orbitals. Therefore, the valence electrons for transition metals cannot be easily determined solely based on the group number.
Remember that the valence electrons determine an element's reactivity and its ability to form chemical bonds.