How to refer to periodic table in order to predict the number of valence electrons?

You can have a general rule according to the group number. Elements in group I will have 1 valence electron, elements in the group two will have two valence electrons in the group 3 they will have three valance electrons and so on and two group eight

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na

Idon't know hope someone you