What can we tell about valence electrons and electron shells if we look at periods and groups

Periods correspond to the relationship of orbitals, or likely areas in which electrons will be found, inside the outermost shell of the atom. Successive periods down the table correspond to atoms with a more electron-rich core of inner shells.

Explanation:

rising temperatures because when water vapor in the air is cooled, it condenses. it turns back into a liquid and attaches to dust particles in the air. these very small water droplets group together to form clouds