the periodic table

Question 1

In what order are elements arranged in the groups of a periodic table?

Answer 1

in the increasing number of electrons in the outermost shell.

Question 2

What are valence electrons?

Answer 2

Valence electrons are the electrons on the outermost shell. They are responsible for the chemical properties of an element. Valence electrons are arranged in increasing numbers on the periodic table, so the elements in those groups have similar chemical properties.