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Atoms and the periodic table


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Atoms and the periodic table

  1. 1. Atoms on the Periodic Table December 17, 2012
  2. 2. Objectives1. Describe the present model of the atom explaining electrons, neutrons, and protons
  3. 3. Periodic TableAtoms make up all matterElements are any material that is made upof only one type of atomElements are organized onto the periodictable
  4. 4. Each element is designated an atomicsymbol on the periodic table
  5. 5. AtomsAtoms cannot beseen with visible lightRobert BrownFirst to discover directevidence of the atom
  6. 6. An Atom is made up of three parts: Protons Neutrons Electrons
  7. 7. ElectronsElectrons surround the nucleus in anelectron cloudElectrons carry a negative chargeThe atom is mostly empty space
  8. 8. Electron Cloud Model
  9. 9. Why don’t we pass through one another?Electrical repulsion – two electrons withnegative charges will repel each other
  10. 10. ProtonsProtons and neutrons are bound to theatomic nucleusProtons carry a positive chargeProtons are identified by Atomic numberatom is electrically neutral: Number ofprotons = number of electrons;
  11. 11. NeutronsNeutron has no electrical charge, but thesame mass as a protonProtons and neutrons are called nucleonsMass given to each proton and neutron is 1
  12. 12. Atomic Mass• Electrons are so small they are considered negligible in mass• Atomic mass is measured in the unit – amu  Atomic Mass Unit Atomic mass on the periodic table
  13. 13. Agenda Bell work • Where is each particle• Notes: Mass Number, below found? What is Isotopes and Ions it’s charge? – Proton• Practice WS – Neutron – electron• History of the Atom Project • Define the following: – Atomic Number – Atomic Mass • Finish yesterdays WS
  14. 14. Mass Number, Isotopes and Ions December 18, 2012
  15. 15. Electrons are so small they are considered negligible in mass Protons and neutrons in the nucleus• Atomic mass is measured in the unit – amu  Atomic Mass Unit
  16. 16. Atomic MassAtomic mass on the periodic table –average of all its isotopesIsotope – an Element with differingnumber of neutrons
  17. 17. Mass NumberMass number = total number of protonsand neutronsIdentify isotopes by the mass number
  18. 18. Writing Isotopic SymbolsX = element symbolA = Mass NumberZ = Atomic NumberTotal number of neutrons: Mass Number – Atomic number = number of neutrons
  19. 19. Isotopic NotationHydrogen - 2, has one proton and oneneutronHydrogen - 3, has one proton and twoneutrons
  20. 20. IonsAtoms that gain or lose electronsLose electrons – positive in chargeGain electrons – negative in charge
  21. 21. Hydrogen that has lost an electron H+1Hydrogen that has gained an electron H-1