The groups (left to right) are numbered from 1 to 18. they arent numbered any other way.
period (up to down.) are numbered from 1-7
Answer:
The bonds between the molecules of the plastic bottle become weaker as the altitude decreases.
The vertical columns on the periodic table are called groups or families<span> because of their similar chemical behavior. All the members of a </span>family<span> of </span>elements<span> have the</span>same<span> number of valence electrons and similar chemical properties</span>
