How Does The Periodic Table Work

Learn the basics about the periodic table, and how the elements are organised within it in this video. The periodic table consists of 7 rows called Periods, going across, and 18 columns, called Groups going down. The elements in the Periodic Table are arranged according to their atomic number, which is the number of protons in their nucleus. The Period shows the element’s electron shell that is being filled. For example sodium is in Period 3 and Group 1. So it has electronic configuration 2:8:1. Whereas chlorine which is also in Period 3 but Group 17 has electronic configuration 2:8:7. So in both cases it is the third shell that is being filled. The group an element is in gives the number of electrons in the outer shell of an atom of that element. Chemical reactions are to do with movement of electrons. So, as all elements in a particular group have the same number of outer shell electrons they have similar chemical reactions. There are trends in properties across Periods. Find out what they are in this video!