The Periodic Table

What is the periodic table? A table where all of the known elements are arranged according to atomic # Mendeleev-first p. table arranged by atomic mass Moseley-out table arranged by atomic #

Which way does a group go? Groups – vertical column (also known as a family) of elements with similar properties The column dictates the number of valence electrons an atom has Numbered 1-18 (Most important 1,2,13-18) Valence Electron – electron in the outer most energy level

Which way does a period go? Period – horizontal row of elements that contain increasing numbers of protons and electrons as you move right across table Each row in the period ends when the outer energy level is filled Numbered 1-7

How do you know how many electrons are in the outer energy level? The number of valence electrons tells you how many electrons are in the outermost energy level. This is dictated by which group the element is in on the table. Group 1 = 1 valence electron Group 2 = 2 valence electron Group 13 = 3 valence electron Group 14 = 4 valence electron Group 15 = 5 valence electron Group 16 = 6 valence electron Group 17 = 7 valence electron Group 18 = 8 valence electron = FULL SHELL = OCTET

Electron Dot Diagrams Use the element Symbol & Valence Electrons Place one dot on each side of imaginary square around symbol until there is one on each side and then partner if needed There should never be more than two dots per side of square Maximum = 8 electrons (2 per side) Al Ne Li

Exit Ticket Which elements are the most reactive?