Why are some elements more reactive than others?

All other atoms have less stable electron numbers, so they react with each other and share electrons to be more stable. The most reactive elements tend to be short one or two electron or have one or two extra electrons.

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

Sorry i dont understand the question can you rephase it?