Atomic Structure Timeline Use the following information to complete the lecture handout. On tomorrows quiz, you will be expected to draw the atomic models match scientists to their experiments and discoveries place the models in chronological order
Democritus (400 B.C.) Proposed that matter was composed of tiny indivisible particles Not based on experimental data Greek: atomos
Alchemy (next 2000 years) Mixture of science and mysticism. Lab procedures were developed, but alchemists did not perform controlled experiments like true scientists. John Dalton (1807) British Schoolteacher based his theory on others experimental data
Billiard Ball Model atom is a uniform, solid sphere John Dalton Daltons Four Postulates 1. Elements are composed of small indivisible
particles called atoms. 2. Atoms of the same element are identical. Atoms of different elements are different. 3. Atoms of different elements combine together in simple proportions to create a compound. 4. In a chemical reaction, atoms are rearranged, but not changed. Henri Becquerel (1896)
Discovered radioactivity spontaneous emission of radiation from the nucleus Three types: alpha () - positive beta () - negative gamma () - neutral
J. J. Thomson (1903) Cathode Ray Tube Experiments beam of negative particles Discovered Electrons negative particles within the atom
Plum-pudding Model J. J. Thomson (1903) Plum-pudding Model positive sphere (pudding) with negative electrons (plums) dispersed
throughout Ernest Rutherford (1911) Gold Foil Experiment Discovered the nucleus dense, positive charge in the center of the atom Nuclear Model
Ernest Rutherford (1911) Nuclear Model dense, positive nucleus surrounded by negative electrons Niels Bohr (1913) Bright-Line Spectrum
tried to explain presence of specific colors in hydrogens spectrum Energy Levels electrons can only exist in specific energy states Planetary Model
Niels Bohr (1913) Bright-line spectrum Planetary Model electrons move in circular orbits within specific energy levels Erwin Schrdinger (1926)
Quantum mechanics electrons can only exist in specified energy states Electron cloud model orbital: region around the nucleus where e- are likely to be found
Erwin Schrdinger (1926) Electron Cloud Model (orbital) dots represent probability of finding an enot actual electrons James Chadwick (1932) Discovered neutrons
neutral particles in the nucleus of an atom Joliot-Curie Experiments based his theory on their experimental evidence James Chadwick (1932)
Neutron Model revision of Rutherfords Nuclear Model
Cinquain The Definition An unrhymed poem consisting of five formatted lines. Mantis Stick Predator Stalking, preening, searching Slenderly fashioned by nature Killer Cinquains do not have titles. However, the first line serves as the announced topic.
RESISTANCE Ohm - Unit for resistance Circular Wires Circular mils 1000 mils = 1 inch RESISTANCE Malleability- property of a metal to be deformed by compression without cracking or rupturing. Ductility- In a tensile test, ductile metals show considerable elongation...
What if Robert Frost was talking about the choice that stands before us daily in every situation? Do we take the path leading to the tree with the fruit of the flesh, or the other path leading to the tree...
Weber's law. Answer. c) a difference threshold. ... the following reflects the notion that pitch is related to the number of impulses travelling up the auditory nerve in a unit of time? Place theory. Frequency theory. Volley principle. Sound localization.
"Ora non si vede più il rapporto tra sequenze evolutive universali e condizionamenti della L1 come uno di esclusione reciproca, ma si tratta piuttosto di determinare quali aspetti di una particolare interlingua possano essere descritti come prodotto di strategie universali...
Types of Portraiture Photography. The basic definition of portrait photography is photography of a person or group to capture the personality of the subjects using various lighting, backgrounds, and techniques. ... Pet photography should elevate pictures of animals into a...
Make this an important part of your classroom expectations and clearly define how you intend to use them in your instruction. Again. And again. Make personal devices an extension of student learning, just as pencil and paper are. Recognize there...
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