compare and contrast two elements in terms of there groups and periods atomic numbers, and numbers of outtermost electrons based on there locations

Question

i need this cuz im studying about it i dont know id=f this cite works hopefully it can help

Answer 1

Emily, 

The elements are divided by periods or groups, and series. Elements within the same period have similar reactions with other elements because they have the same number of outer electrons (valence electrons) to the total possible outer electrons. Elements within the same series have the same outer shell of electrons, but not the same number of outer shell electrons. The question is asking you to just pick two elements, and write up a compare/contrast using the information you know from the periodic table. 

For instance, H and He.

Two gases that are close to each other in atomic number, 1 and 2, but vastly different in how they act. H is highly reactive because it only has 1 outer shell electron out of 2 possible outer electrons. He is not very reactive at all, because it has 2 outer shell electrons out of 2 possible outer shell electrons. H is in period I, where He is in period VIII. Every element in period I has only 1 outer shell electron, while every element in period VIII, has its outer shell completely full.