C3.1 Periodic table 0.0 / 5 ? ChemistryThe Periodic TableGCSEAQA Created by: lridgewayCreated on: 04-06-17 16:16 Newlands Called table of Octaves Didn't have spaces for undiscovered elements Wrong atomic masses were calculated Pattern he found was false Some elements were mixed 1 of 6 Mendeleev Saw problems in Newlands periodic table Recalculated atomic mass Placed in order we know today Left spaces for undiscovered elements 2 of 6 Modern periodic table More information about protons, neutrons and electrons Placed in order of atomtic number (proton number) 3 of 6 Group 1 (alkali metals) Reactivity increases as you go down the group REASON: atom size increases, forces of attraction weaker as electron further from positive nucleus, easier to take electron Melting-point and boiling-point decrease down the group REASON: less energy is needed to break larger atoms due to weaker forces of attraction 4 of 6 Group 7 (halogens) Exsist as diatomic molecules Reactivity decreases as you go down the group REASON: atoms increase in size, force pulling in electrons becomes weaker as its further from nucleus, electrons feel weaker positive force Melting-point and boiling-point increase as you go down the group REASON: diatomic molecule size increases, stronger intermolecular forces, more heat needed to break them 5 of 6 Transition metals Most do not react vigirously with water and oxygen (Iron does) High melting-point and high density (except Mercury) Strong and hard No set pattern, form different ions Form coloured compounds Useful catalysts 6 of 6
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