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Atoms and the Periodic Table Notes- Chapter 4 Atomic Structure Timeline Democritus (400 B.C.) • Proposed that ___________________ was composed of tiny _______________________ particles • Not based on ______________________________ data • Greek: ___________________________________ Alchemy (next 2000 years) • Mixture of _________________________ and ______________________________. • Lab procedures were developed, but alchemists did __________________perform ______________________ experiments like _________________ ______________________ John Dalton (1807) • British Schoolteacher – • _________________ ________________ Model – • based his ________________on others’ __________________ data atom is a ______________________________________________ Dalton’s Four Postulates 1) Elements are composed of ______________ _______________ particles called ________________________. 2) ______________________ of the same _______________________ are ____________________. Atoms of __________________ _________________ are __________________________________. 3) Atoms of different elements ______________________ together in simple proportions to create a compound. 4) In a chemical ________________________, atoms are ________________________, but not changed. Henri Becquerel (1896) • Discovered _______________________________ – spontaneous _____________________ of radiation from the _________________________ • Three types: – ________________________ () - positive – ________________________ () - negative – _________________________ () - neutral 1 J. J. Thomson (1903) • Cathode Ray Tube Experiments – beam of negative particles • Discovered Electrons – negative particles within the atom • Plum-pudding Model – positive sphere (pudding) with negative electrons (plums) dispersed throughout Ernest Rutherford (1911) • _____________________ _______________ Experiment • Discovered the _________________________ – dense, __________________charge in the _________________ of the atom • Nuclear Model – dense, positive nucleus surrounded by negative electrons Niels Bohr (1913) • _______________-_______________ Spectrum – tried to explain presence of specific _____________ in _______________ __________________ • Energy Levels – __________________ can only exist in specific __________________ ___________________ • Planetary Model – _________________ move in _________________ orbits within specific energy levels Erwin Schrödinger (1926) • Quantum mechanics – _______________ can only exist in specified ____________ ___________________ • Electron cloud model – ___________________: region around the _______________ where ____________ are likely to be found • _______________ represent ________________________ of finding an e- not actual electrons 2 James Chadwick (1932) • Discovered ______________________ – _________________ particles in the _______________ of an atom • __________________________ Experiments – based his theory on their _______________________l evidence • Neutron Model • revision of _____________________________Nuclear Model Structure of the Atom A. Chemical Symbols • _______________________ matter! • Element symbols contain ______________ ______________ letter followed by ______________________ letter(s) if necessary. Metal that forms bright blue solid compounds. B. Subatomic Particles Co vs. CO ATOM NUCLEUS • Poisonous gas. ELECTRONS PROTONS NEUTRONS POSITIVE CHARGE NEUTRAL CHARGE NEGATIVE RGE Quarks – ____________ types – ______ quarks = 1 proton or 1 neutron 3 II. Electron Cloud Model A. Orbital • Region where there is _________________ probability of finding an _____________________. • _____________ pinpoint the _________________ of an __________________________. • _____________________ of __________________ represents degree of ______________________. • Orbitals have different shapes. s p d B. Energy Levels • _________________ can only exist at certain energy levels. • ___________energy levels are ________________ to the _______________. • Each energy level (n) can hold 2n2 electrons. C. Bohr Model Diagrams • Simplified energy levels using Bohr’s idea of circular orbits. Lithium Atomic #: 3 Mass: 7 # of p: 3 # of e: 3 # of n: 4 Can replace with ___ p ___ n Maximum e - Level 1 ___ e - Level 2 ___ e Level 3 ___ e - - Level 4 ___ e - The Periodic Table I. History of the Periodic Table Mendeleev Mosely • Dmitri Mendeleev (1869, Russian) - ____________________ elements by increasing ______________________. - Predicted the existence of ____________________ ____________________________ 4 • Henry Mosely (1913, British) – _______________ elements by increasing ______________________________________. – Fixed problems in Mendeleev’s arrangement. II. Organization A. Metallic Character • _______________________ • _______________________ • _______________________ B. Terms • Periods - horizontal ______________ in the periodic table that represents the energy _____________ • Group - vertical __________________ in the periodic table that represents the number of _______________ electrons (also called _________________) III. Periodic Trends A. Terms • Periodic Law - _____________________________________________________________________________ _____________________________________________________________________________ • Valence Electrons – ___________________ in the _______________________energy level • First Ionization Energy - _______________ required to _______________________ an ________ from a neutral atom B. Periodic Trends • Atomic Radius - __________________ to the ______________ and _________________ 1 2 3 4 5 6 7 • First Ionization Energy - _________________ to the ____________________ and ______________________ 1 2 3 4 5 6 7 5 • • • Which atom has the larger radius? – Be or Ba – Ca or Br Which atom has the higher 1st I.E.? – N or Bi – Ba or Ne _________________= # of __________________________ (except He) – _________________________ have similar _______________________. • ________________________ = # of _____________________________________ Masses of Atoms A. Atomic Mass • atomic mass unit (u or amu) • 1 u = 1/12 the mass of a 12____ atom - 1 __________________ = 1 u - 1 __________________ = 1 u - 1 u = 1.67 10-24 g B. Mass Number • ___________ of the ________________ and _______________ in the _______________ of an atom. • Always a ____________________ number. • _____________ = _______________________________________ • © Addison-Wesley Publishing Atoms of the same __________________ with ___________________ numbers Company,ofInc. ____________________________. • Isotope symbol: C. Isotopes Mass # Atomic # 12 6 C “Carbon-12” 6 • Average Atomic Mass – reported on Periodic Table – ________________ average of ____________ isotopes Equation: • EX: About 8 out of 10 chlorine atoms are chlorine-35. Two out of 10 are chlorine-37. Equation: Families of Elements Think of each element as a member of a family that is also related to other elements nearby. I. Elements are classified into three categories A. ________________ • shiny ____________; good conductors of ___________ and _________________. B. ________________ • all found on the _____________ side of the periodic table (except for ___________) • can be solids, ________________, or gases C. _______________ or __________________ • nonmetals that can conduct _____________ and ________________. 7 8