One is per se acidic
Other one is per force alkaline
Their life is neutralized
One is corrosive
Other is effervescent
Together is balanced
One is hydrogen
Other is oxygen
They quench their thirst
In 2:1 proportion  
One is proactive
Other is reactive
Both are coactive
One is productive
Other is seductive
Couple is reproductive
They build nucleus family
With atomic character
Explode or implode
Implore and explore
New order of life’s disorder
The duo’s duel disposition
Sports harmonious melody