Visit this website to view the periodic table. In the periodic table of the elements, elements in a single column have the same number of electrons that can participate in a chemical reaction. These electrons are known as “valence electrons.” For example, the elements in the first column all have a single valence electron, an electron that can be “donated” in a chemical reaction with another atom. What is the meaning of a mass number shown in parentheses?
Cut Rita Zahara
“The Periodic Table of the Elements ,” Open Educational Resource (OER) , accessed March 1, 2021, http://oer.iain-padangsidimpuan.ac.id/items/show/933.