For each group write the # of valence electrons

Explanation:

Bascially just count starting from 1 (skip the transition metals) and put helium at 2 valence. Everything else is just a regular pattern.

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.