P.12.A.2 - Students know elements in the periodic table are arranged into groups and periods by repeating patterns and relationships. Able to identify the positions of and explain why elements in the main groups of metals, non-metals, alkali metals, alkalinie earth metals, halogens and noble gases in the periodic table have similar properties. Able to classify elements as metals and non-metals. Able to know the difference between and predict periodic trends of atomic numbers and mass. Able to calculate the number of electrons, protons and neutrons given the atomic number or mass for a given isotope of any element.