Answer:
Groups I & II
Step-by-step explanation:
The most reactive metal groups on the periodic table are metals of group 1 and II. 
Group I elements are the alkali metals
Group II elements are the alkali earth metals
- The most reactive metallic group of metals are the alkali metals. 
- They are followed by metals in the second group which are the alkali earth metals. 
Therefore, elements in groups I and II are the most reactive metallic groups. 
Group I elements prefers to lose one electron to attain an octet configuration. 
Group II elements prefers to lose two electrons.