The elements in Groups 1 AU) and 7A (17) are all quite reactive. What is a major difference between them?

Elements of group 1A are known as alkali metals. Elements of this group are lithium, sodium, potassium, rubidium, cesium, and francium.

All these elements are metals and every element of this group has 1 valence electron. So, in order to attain stability they will readily lose their valence electron.

Hence, elements of group 1A are very reactive.

On the other hand, elements of group 7A are also known as halogen group. Elements of this group are fluorine, chlorine, bromine, iodine, and astatine.

All these elements are non-metals and every element of this group has 7 valence electrons. So, in order to completely fill their octet these elements gain 1 electron from a donor atom.

Therefore, these elements are alo reactive in nature.

But the major difference between elements of group 1A and group 7A is that elements of group 1A are metals but elements of group 7A are non-metals.