How is the element alike in the group and the period on the periodic table?

Answer 1

FOR THE SIZE

the elements on the Periodic Table

decreases across the period

and increases down the group

FOR THE ELECTRON DIFFERENCE

For the first 20 element

across the period the difference between two closes element is +1 eletron or -1 eletron

down the group the difference between two closes element is +8 eletron or -8 eletron

Answer 2

Elements in the same group have similar chemical properties because they have the same number of electrons in their outermost energy level, which determines their reactivity. Elements in the same period share the same number of electron shells, leading to similarities in valence electron configuration and atomic size.